INVESTORS raised their bullish bets on most Asian currencies over the past two weeks, with long positions on the Malaysian ringgit at their highest since March 2016, a Reuters poll showed, as the dollar came under pressure after doubts about the prospects of U.S. tax reforms showed no signs of abating.

The dollar touched a near one-month low on Wednesday after a tax plan that would repeal the Obamacare mandate and give permanent tax cuts only to U.S. corporations drew fire from two Republican lawmakers, in what could be a sign of trouble for the sweeping measure.

"The task of passing the Senate tax bill may have just gotten harder with lawmakers inserting a repeal of the Obamacare personal mandate provisions," said Greg McKenna, chief market strategist at CFD and FX provider AxiTrader.

"It may have just made the President's Christmas timetable a little harder to meet."

Investors have increased their bullish bets on the ringgit, the South Korean won and the Thai baht, the poll of 10 respondents showed.

Bullish sentiment on the ringgit was at its highest in more than 19 months, buoyed by the central bank's positive tone on the domestic economy.

Sentiment also got a boost from expectations that third-quarter economic growth will match the brisk pace seen in April-June, highlighting the resilience of the manufacturing sector.

Furthermore, full-year inflation is expected to come in at the higher end of Bank Negara Malaysia's forecast of 3-4 percent, before moderating next year. This increases the chances of a rate hike in the near future.

The ringgit touched a one year-high on Thursday, rising 7 percent so far this year.

Among other currencies, long positions on the Korean won touched the highest since July as investors cheered the hawkish signals from the central bank amid expectations of robust growth and inflation.

The International Monetary Fund said on Tuesday it expects South Korea's economy to expand by 3.2 percent this year, slightly faster than its previous forecast.

Recent bullish sentiment around the won has also been underpinned by rising inflows, with foreign investors turning net buyers for the first time since June.

Long positions on the Singapore dollar rose five-fold as investors became more optimistic about the pace of economic growth after factory activity in October expanded the most since December 2009.

It was not all beer and skittles though, with investors continuing to be bearish on the Philippine peso after the central bank left its key interest rate steady last week and signalled it was in no rush to alter policy settings.

Meanwhile, traders trimmed their long positions on the Chinese yuan over concerns about the economy, with last month's industrial output, fixed asset investment and retail sales missing expectations.

The Asian currency positioning poll is focused on what analysts and fund managers believe are the current market positions in nine Asian emerging market currencies: the Chinese yuan, South Korean won, Singapore dollar, Indonesian rupiah, Taiwan dollar, Indian rupee, Philippine peso, Malaysian ringgit and the Thai baht.

The poll uses estimates of net long or short positions on a scale of minus 3 to plus 3. A score of plus 3 indicates the market is significantly long U.S. dollars.

The figures include positions held through non-deliverable forwards (NDFs).