US President Obama's final State of the Union address

Twitter traffic on the hashtag #SOTU has exploded since President Obama started delivering his final State of the Union address, with more than 761,000 tweets using the tag, up by roughly 500,000 since Obama's speech began.

Jeers at House Speaker Paul Ryan’s lack of participation counted heavily among the tweets. According to social media analytics firm Zoomph, #PaulRyan was among the top hashtags during the speech.

Ryan appeared only to have applauded Obama when the president mentioned U.S. military personnel.

Author and New York Times columnist Anand Giridharadas (@AnandWrites) tweeted: "After curing cancer, we should cure the problem that prevents Paul Ryan's hands from joining even for things he agrees with. #SOTU."

EARLIER DEVELOPMENTS (ALL TIMES ET)

9:38:26 PM

While President Barack Obama was widely expected to focus on gun control in his final State of the Union address, the word "gun" appeared just once in the prepared text of his speech when he quickly summarized several proposals he's already made.

Obama symbolically had a chair left empty in the box where First Lady Michelle Obama was sitting in honor of those who have died from gun violence. The hashtag #EmptySeat was trending heavily on Twitter in response to the gesture.

The single reference to "gun" compared with four mentions of "climate change" and 15 to the "economy."

Obama apparently has delivered on his promise to keep this year's speech shorter: The text of his speech unofficially comes in at 5,438 words versus 6,776 in his 2015 speech.

9:22:21 PM

The White House released a post (http://bit.ly/1Q3P2oz) by Vice President Joe Biden explaining his new task, heading an initiative to find a cure for cancer.

President Barack Obama was expected to detail Biden's role during the State of the Union speech Tuesday night.

"I know that we can help solidify a genuine global commitment to end cancer as we know it today — and inspire a new generation of scientists to pursue new discoveries and the bounds of human endeavor," Biden wrote.

9:13:00 PM

President Barack Obama has entered the U.S. House of Representatives to deliver his final State of the Union speech as U.S. commander in chief.

Obama has taken the podium and has begun.

He promises to keep this speech, his eighth, "a little shorter," joking that many in the audience need to get to Iowa, site of the first U.S. party caucuses ahead of November's presidential election.

According to an advance text of his speech, he will rebuff talk from critics that America is in economic decline as "political hot air."

9:04:57 PM

President Barack Obama will call on Congress to end the practice of drawing congressional districts so that politicians can pick their voters.

Too many Americans feel "the system is rigged in favor of the rich or the powerful or some narrow interest," Obama said, according to a copy of the speech released by the White House.

First Lady Michelle Obama has arrived in the House chamber for her husband's final State of the Union address, wearing a mustard-colored dress. Members of Obama's cabinet have also arrived, as have the justices of the U.S. Supreme Court. 8:56:55 PMThe White House has posted the text of President Obama's speech (http://bit.ly/1nh7MFI) and he will describe ISIS militants as "killers and fanatics who have to be rooted out, hunted down and destroyed."

Separately, however, he said claims that the ISIS fight is World War III are "over the top." Still, he urged Congress to pass authorizations to use military force against ISIS.

Obama is also expected to say that Vice President Joe Biden, whose son Beau died from a brain tumor, will lead a new effort to make America the country that cures cancer once and for all.

8:49:53 PM

U.S. Vice President Joe Biden has entered the House of Representatives chamber ahead of President Obama's State of the Union address, shaking hands with several of members as he arrived.

House Speaker Paul Ryan, attending his first State of the Union in his new capacity, greeted the vice president as he walked up the steps. "How's it going Joe?" Ryan said.

The two men aren't strangers. They debated during the 2012 campaign as the respective vice presidential nominees for their parties.

Also spotted on the House floor: Former Congresswoman Gabby Giffords and Democratic presidential candidate Bernie Sanders.

Obama, meanwhile, is enroute to Capitol Hill from the White House. The White House posted video on Snapchat of him climbing into his car, nicknamed The Beast.

8:36:29 PMWith about 30 minutes to go until the State of the Union, social media traffic was heavy, with the hashtag #SOTU tweeted more than 171,000 times.

Other top hashtags on Twitter, according to social media analytics firm Zoomph, include #kimdavis, referring to the woman who was jailed last year over the same-sex marriage license controversy but then invited to the speech. Also in the mix were #tcot, referring to "Top Conservatives on Twitter" and #P2, a hashtag for progressives.

Republican presidential hopeful Ben Carson took to Twitter to criticize Obama for speaking while American military members were being held in Iran. "When President Obama takes the stage tonight, there will still be 10 United States military members being held captive by Iran," Carson tweeted. 8:26:15 PMPresident Barack Obama has no plans to speak about the Iranian seizure of U.S. Navy sailors in his final State of the Union address, CNN reported Tuesday.

"There are no plans to address this issue," White House communications director Jen Psaki said in a CNN interview. "He's tracking this closely, he’s following this closely but the State of the Union will not be about this issue."

The president will, however, "absolutely" tout the nuclear deal he reached with Iran and other world powers last year, she said.

In the latest development on the seizure, a U.S. defense official said plans were in place for Iran to return the 10 sailors to a U.S. Navy vessel in international waters early on Wednesday. 8:05:43 PMPresident Barack Obama on Tuesday urged U.S. leaders to "fix our politics" and lift Americans' standard of living in a final State of the Union speech designed to contrast his vision for the country with Republican presidential campaign rhetoric.

Obama, who is delivering his last annual speech to Congress before leaving office next January, said political discourse was meant to be messy, but - in an apparent nod to proposals by Republican candidates such as Donald Trump - required "bonds of trust" between citizens.Obama's speech, scheduled for 9 p.m. EST (0200 GMT on Wednesday), is one of his few remaining chances to capture the attention of millions of Americans before the Nov. 8 election of a new president who will take office next January.

7:52:40 PM

In the latest teaser leading up his State of the Union address on Tuesday night, President Barack Obama touted his record on the economy and health care.

"More than 14 million jobs, nearly 18 million people now with health coverage -- together, we've pulled ourselves out of yesterday's crisis to put us on a stronger course for tomorrow," Obama said in the message posted at www.whitehouse.gov.

Still, Obama said his speech will stay focused on the future.

"Tonight I'll lay out a vision for an economy that's even stronger, a country that's safer, and a union that's more perfect.

"Because with one year left in my presidency, I'm still fired up and ready to go."

6:59:43 PM

In the White House's latest Snapchat clip ahead of the State of the State speech, Edith S. Childs, the retired nurse who coined President Obama's notable "Fired up" campaign chant in 2008, is shown singing the refrain.

Wearing a cream-colored suit and pumping her fist, Childs is featured on The White House Official Snapchat Story singing: "Fired up! Ready to go!" again and again.

Childs will be a special guest of First Lady Michelle Obama. 06:43:51 PM

President Barack Obama is set to tell Americans on Tuesday that while the country faces extraordinary change, the nation can overcome the challenges it faces if Americans come together, the White House said.

"It will only happen if we fix our politics," Obama will say, according to excerpts of his State of the Union address provided by the White House.

"The future we want - opportunity and security for our families; a rising standard of living and a sustainable, peaceful planet for our kids - all that is within our reach," will say.

6:16:53 PMPresident Barack Obama made a brief appearance on Facebook on Tuesday as he finalized the text of his last State of the Union address.

The president, sitting at his desk, said he was making last minute changes and added touches to his speech.

"There's a lot of work that still needs to be done," Obama said, adding that he wanted to make sure that the American people understood his proposals. "We've got some big choices ahead," he said. 6:06:01 PM

Hardly a quiet few hours for the White House in the run up to President Obama's swan song State of the Union address later on Tuesday.

As the president goes through his final preparations for the speech:

Iran has taken 10 sailors aboard two U.S. Navy boats into custody, although Iran has told the United States that the crew members will be "promptly" returned, U.S. officials said.

And at least 145 congressional Democrats, including Senate Minority Leader Harry Reid, are condemning the Obama administration's immigrant deportation efforts.

6:00:01 PM

Ahead of his final State of the State speech, the White House tweeted that President Barack Obama would share a few thoughts live on Facebook before the event.

Obama's speech before a joint session of Congress is scheduled for 9 p.m. ET.

Meanwhile, indie rock band EL VY was gearing up for the pre-speech performance at 7:45 p.m. ET. The White House posted clips of the band's warm up on Snapchat.

3:59:38 PM

U.S. President Barack Obama will talk about the prospects for self-driving cars in his final State of the Union address on Tuesday, according to government officials, the first time the president has used the annual speech to tackle an important issue facing the auto and technology industries.

2:27:44 PM

Millions of Americans were discussing President Obama's upcoming State of the Union address on Tuesday on top social media platforms like Facebook and Twitter, debating anticipated speech topics such as gun control, terrorism and healthcare.

2:05:14 PM

U.S. President Barack Obama voiced regret for failing to unite Washington since taking office on a wave of hope in 2009, as he prepared to give a State of the Union speech on Tuesday to launch his final year in the White House.

Asked about his inability to heal America's political divisions, Obama told NBC's "Today" show, "It's a regret."

The president planned to speak optimistically about America's future in his speech in Congress, one of his few remaining chances to capture and hold the attention of millions of Americans before the Nov. 8 election of a new president who will take office next January.

The Democratic president will give his final State of the Union address as campaign rhetoric for November's presidential election intensifies with candidates fighting over illegal immigrants, wage inequality and violence. 9:00:22 AMPresident Barack Obama said he could envision Republican presidential candidate Donald Trump giving a State of the Union address - but in a comedy skit.

In a "Today" show interview ahead of his final State of the Union address, the Democratic president was asked if he could envision Trump, the billionaire developer known for his bombastic style, making his own State of the Union speech as president.

"Well, I can imagine it - in a 'Saturday Night' skit," Obama said, referring to the NBC's long-running late-night comedy show "Saturday Night Live."

"Look, anything's possible. And I think, you know, we shouldn't be complacent."