WASHINGTON (WASHINGTON POST) - As United States President Donald Trump faced a critical vote on his impeachment on Thursday (Dec 12), his top political advisers said the process has already begun to reap benefits for his re-election campaign.

"This lit up our base, lit up the people that are supporters of the president. They're frustrated, they're upset, and that motivates voters," campaign manager Brad Parscale told reporters during a briefing on Thursday. "They have ignited a flame underneath them."

Mr Parscale - who prefaced his remarks by saying he did not believe Mr Trump deserved to be impeached - said that "every metric" he tracks, from fund raising to voter sentiment to volunteer recruitment, shows a political benefit for the president.

"That has put money in our bank, it has added volunteers to our field programme," he said. "It's filled up the rallies easier."

The characterisation of Mr Trump's expected impeachment as a political upside stands in stark contrast to the tone struck this week by many Democratic lawmakers, who have said repeatedly that they are "sad" and "sombre" that Mr Trump's alleged misconduct with Ukraine has forced such a constitutional sanction.

Some Democrats representing districts won by Mr Trump have expressed concern about political blowback, while others have expressed confidence that voting for impeachment was their constitutional duty and more important than politics.

Mr Parscale made his impeachment comments during a briefing by several senior campaign officials about the state of Mr Trump's re-election bid.

The officials - most of whom spoke on the condition of anonymity to discuss internal campaign strategy - sought to project an air of confidence in Mr Trump's re-election chances, using an elaborate slide show to explain why the president was strongly positioned to be elected to a second term.

The briefing did not reference impeachment until a question-and-answer period that followed an hour-long presentation about the state of Mr Trump's re-election campaign.

During that presentation, campaign officials argued that Mr Trump's fund raising, record of accomplishments and more professional political apparatus give him a better chance to win than he had in 2016.

Despite approval numbers that have remained underwater throughout his presidency, campaign officials said he would win in part because many voters who had an unfavourable view of the president would likely vote for him due to his policies and the state of the economy.

The officials credited Mr Trump with a takeover of the Republican Party, pointing to his high approval ratings within the GOP.

"The Republican Party used to be the wine and cheese party," one official said. "Now it's the beer and blue jeans party."

GOP chairman Ronna McDaniel said Mr Trump has been able to retain support from standard conservatives by embracing traditional Republican policies, while also reaching out to new voters.

"I think he has actually expanded the party," she said. "But he's retained a lot of the core elements of the party, that's why so many Republicans support him."

Mr Jared Kushner, Mr Trump's son-in-law and a senior White House adviser who is expected to play a significant role in his re-election campaign, said Mr Trump is redefining the party in his image.

"I was not a Republican. Now I'm a Republican," Mr Kushner said. "I think the Republican Party is growing now that people like me feel comfortable being part of it."

Mr Kushner pointed to the raft of Republican retirements in Congress, saying that many of the outgoing lawmakers are from heavily pro-Trump districts.

"Old guard cycling out," he said. "A lot of people coming in are inspired by the Trump revolution."

The party is "being redefined", he added.

As measured by Gallup, however, GOP party affiliation has remained flat in recent years. An average of 28 per cent of Americans said they were Republicans in 2019 so far, compared with a similar 27 per cent who said the same in 2012.

Democrats also assert that Mr Trump's behaviour has turned a growing coalition of voters, including minorities, women and suburban moderates, away from the GOP.

Democrats have said Mr Trump's unpopularity is one reason for their historic gains in the 2018 midterm elections, which gave them the House majority they are now using to pursue impeachment.

Mr Trump campaign officials dismissed the 2018 results, saying that the president was not on the ballot that year. The campaign is targeting almost nine million voters who sat out the 2018 election but support Mr Trump, officials said.

On Thursday, Mr Trump used his Twitter account to mock Greta Thunberg, the Swedish 16-year-old climate activist, calling her distinction as Time magazine's Person of the Year "ridiculous" and suggesting that she work on anger-management issues and go to a movie with a friend.

The contrast between Mr Trump's incendiary tweet attacking a teenage girl and his campaign's highly professional slide show laying out his path to victory underlines a major theme of the 2020 race.

While Mr Trump is armed with more staff, more money and more data this time than he had in 2016, he continues to operate as his own strategist - and has shown no willingness to curb antics that many voters find offensive.

Mr Parscale said the impeachment process is helping in the effort to grow the president's base, including by swaying independent voters to Mr Trump's side. He cited internal polling that he has shared online about the unpopularity of impeachment in swing congressional districts.

His remarks echoed Mr Trump's claims that impeachment was helping him politically. At a rally on Tuesday, Mr Trump said House Speaker Nancy Pelosi had made a mistake by pursuing impeachment.

"Our poll numbers have gone through the roof because of her stupid impeachment," he said.

In fact, his overall approval rating has barely budged since the launch of the impeachment inquiry, remaining in the low 40s.

Since public hearings began, support and opposition for Mr Trump's impeachment and removal from office has been split, 47 per cent to 45 per cent according to a Washington Post average.

Both parties are largely united in their opinions, according to the Post average: 87 per cent of Republicans are opposed to impeachment and removal, while 86 per cent of Democrats are in favour.