NEW YORK (Reuters) - Most Democrats want to impeach U.S. President Donald Trump, even if that means weakening their party’s chances of winning back the White House in the 2020 election, according to a Reuters/Ipsos opinion poll.

The poll, conducted on Monday and Tuesday, found that 55% of Democrats said that their party leaders should press ahead with impeachment even “if it means a lengthy and expensive process that could weaken their chances of winning the presidency in 2020.”

And even a higher number - 66% of Democrats - agreed that Congress should pursue impeachment, “even if that means they will need to postpone efforts to pass laws that could benefit me.”

Overall, the poll found that support for impeachment remains unchanged overall among all Americans - holding at 45% since last week. But opposition to impeachment dropped by 2 percentage points from last week to 39%.

Among those who identify as Democrats, 79% said Trump should be impeached, up 5 percentage points from a similar poll that ran Sept. 26-30. Only 12% of Republicans and about 1 in 3 independents supported impeachment, which is mostly unchanged from last week.

Full poll results: here

Support for impeaching Trump had been rising since late September after an unidentified U.S. intelligence official filed a whistleblower complaint accusing the president of pressuring Ukraine to ensnare Democratic presidential contender Joe Biden and his son in a corruption investigation.

Biden, the former vice president, is an early favorite to win the Democratic presidential nomination, and opinion polls show that he fares better than other Democrats including Senators Elizabeth Warren and Bernie Sanders in a hypothetical general election matchup against Trump.

The whistleblower complaint, denounced by Trump as a “witch hunt” carried out by his political enemies, has since been backed up by a second unidentified whistleblower who has more direct knowledge than the first of some of the allegations in the complaint, according to the person’s lawyers.

FILE PHOTO: U.S. President Donald Trump responds to questions about the U.S. House impeachment investigation during a formal signing ceremony for the U.S.-Japan Trade Agreement at the White House in Washington, October 7, 2019. REUTERS/Kevin Lamarque

Trump, who says he was acting out of his duty to root out corruption, said last week that China should also investigate Biden.

Overall, the Reuters/Ipsos poll showed that 51% of all Americans agreed that Trump “pressured” Ukraine President Volodymyr Zelenskiy to investigate the Bidens, while 27% disagreed.

And 59% agreed that Congress should investigate “if President Trump committed impeachable offenses” as part of his conversation with Zelenskiy.

In general, 39% said they approved of the job Trump was doing and 55% disapproved.

Elaine Kamarck, a senior fellow at the Brookings Institution, said the poll shows how much Democratic voters have lined up behind Democratic House Speaker Nancy Pelosi and moderate House Democrats who had been cautious about pursuing an impeachment inquiry earlier this year.

“That phone call (between Trump and Zelensky) changed everything,” Kamarck said.

“The moderates, Speaker Pelosi, they changed their minds in a very public way in favor of impeachment. They’ve been making their case to the public, and some of them have followed.”

Democratic voter Moneque Jarmon, 51, from Philadelphia said she doubted Trump would be removed from office through the impeachment process. But it was important to set a precedent that the president is accountable for his actions, she said.

“The fact that he tweets every few minutes, the risky behavior he’s doing – he’s advertising that he can do whatever he wants, like he’s the president and nobody can touch him,” she said. “The longer he stays in there, the more damage he’s going to do.”

Jarmon, who supports Biden as an experienced candidate to take on Trump, said Congress had for a long time failed to pass important legislation like gun control, so she doubted an impeachment process would make the situation worse.

The Reuters/Ipsos poll was conducted online, in English, throughout the United States. It gathered responses from 1,118 adults, including 454 who identify as Democrats and 457 who identify as Republicans. It has as credibility interval, a measure of precision, of 5 percentage points.