U.S. President Donald Trump urged Republican U.S. senators on Friday to repeal Obamacare immediately if they cannot agree on a new health care plan to take its place.

Republican leaders have set Friday as the goal for working out changes to Senate legislation that would repeal extensive parts of the 2010 Affordable Care Act, the law dubbed Obamacare that expanded health insurance coverage to 20 million people.

Their efforts were complicated on Thursday by a Congressional Budget Office report that said the Senate proposal would cut spending on government Medicaid for the poor by 35 percent come 2036.

"If Republican Senators are unable to pass what they are working on now, they should immediately REPEAL, and then REPLACE at a later date!" Trump wrote in an early morning Twitter post.

U.S. Senator Ben Sasse, a Republican who has often clashed with Trump, welcomed the suggestion. Sasse said this week he was not satisfied with the Senate healthcare legislation.

"Sounds great, Pres. @realDonaldTrump," Sasse wrote in a response on Twitter. "We are agreed. We need to break the logjam."

Trump promised as a presidential candidate to do away with the Affordable Care Act but crafting a plan acceptable to Republicans, who control both chambers of Congress, has proven easier said than done.

Republicans would like to make progress on that issue to clear the way for other priorities such as tax reform.