“Russia was never real,” said an outside Trump adviser. “Ukraine is.”

High-level Trump supporters who have stood by the president for years are growing increasingly unsettled by his latest strategy of dismissing the latest fight as Russia 2.0. Half-a-dozen senior Republicans, including those who both talk directly to Trump and advise him on everything from campaign strategy to policy to communications to fundraising, said in interviews that they fear the president's plan to tie Russia and Ukraine could be ineffective because it dismisses the seriousness of the allegations and the fact that he admitted his actions.

Trump often likes to poll his confidants for strategic feedback. But the Trump allies said they’re reluctant to challenge the president directly in this case because he's so angry to be facing an impeachment inquiry and so convinced he didn't do anything wrong. Besides, Trump believes his strategy to combat the Russia investigation was a success.

None of the advisers think Trump will be removed from office — not enough Senate Republicans would vote for that — but they say he’s hurt himself in what is expected to be a tight reelection campaign. A Republican close to the president said the notion that impeaching Trump will help his campaign, as some are pushing, is ludicrous. “It isn’t a positive,” the person said flatly.

Trump — who entered the White House with the least government experience in U.S. history — should have left campaign opposition research of Joe Biden to staff, this person said. “What he did showed a lack of sophistication. He showed a lack of familiarity between how the government works and how the campaign works.”

House Democrats officially opened an impeachment inquiry after learning Trump asked Ukrainian President Volodymyr Zelensky to investigate Biden. Trump and his personal attorney, Rudy Giuliani, have accused Biden, while he was serving as vice president, of helping Hunter Biden, who at one time served on the board of a Ukrainian natural gas company, earn money in both Ukraine and China.

Trump has repeatedly insisted Democrats launched the Ukraine investigation because they failed to find any evidence to impeach him after special counsel Robert Mueller concluded what he called the “witch hunt” — the 2-year-long inquiry into the 2016 presidential election.

“This is the greatest hoax. Now, it's gone on for a long time,” he said last week. “We had the Mueller collusion delusion, OK? That went on for years. And that's finally done. No collusion, no obstruction, no nothing. ... Now I get three days of peace ... and I hear about the word impeachment. I said, ‘What did I do now?’“

Democrats are trying to undo the Election regardless of FACTS! pic.twitter.com/cQ3B1bGD4L — Donald J. Trump (@realDonaldTrump) October 2, 2019

White House aides and Trump’s campaign have all pushed the same Russia-Ukraine connection. But it’s a comparison that some of his campaign allies acknowledge is simply false.

“Russia was a complete and utter fantasy,” said a person close to the Trump campaign. “Ukraine isn’t. His actions were unseemly … not a ghost like Russia.”

Other Republicans say the latest form of the Trump defense risks backfiring on the president and his team given the very different circumstances.

Michael Steel, a Republican strategist who worked for the presidential campaigns of Jeb Bush and Mitt Romney, said the Ukraine controversy is much more clear-cut than Russia because Trump was personally involved, he admitted what he did and, perhaps most important, it happened while he already was sworn into office.

"He's president of the United States with all the power and influence that goes with that," Steel said.

Trump admitted he asked Zelensky to look into the Bidens — and then openly called on China to do the same last week. He has insisted there’s nothing wrong with his actions and defends himself in much the same way he did during the Russia investigation — attacking the Democrats, the media and his critics.

"You understand why they want to lump the two together — so in the public's mind they say Russia, Ukraine that's different how?" said Doug Heye, a veteran Republican strategist. "That's the ultimate goal.“

But, he added, “it's clear there are differences. There is a reality."

A former campaign staffer said Trump doesn’t have a lot of experience and comfort talking about certain topics, including foreign policy, and it shows. “He did it because he didn’t know any better,” the person said. “In his mind, he didn’t say anything improper. ... It's naive and shows an almost innocence.”

Trump regularly breaks social norms when speaking to foreign leaders, using blunt language and bragging about accomplishments, some real and some perceived, but Democrats say this time he undermined the Constitution, national security and the integrity of elections.

“I think it was stupid but I see why he did it,” said the outside Trump adviser. “It was an avoidable, unforced error.”

On Friday, Trump tried to characterize his actions more generally. “This is about corruption, not about politics,” he said. But House Democrats had already received documents, including text messages, showing that some senior State Department officials believed aid to Ukraine was contingent on helping Trump’s campaign.

A second Republican close to the president said Trump's problem is that he‘s still so fixated on anyone trying to discredit him during the 2016 election — including former President Barack Obama and his vice president — that he went after Biden. “Should he have mentioned Biden? No,” the person said. “I wish he wouldn’t have. ... But I don’t fault him as much as other people.”

The Trump campaign insists impeachment will help Trump in his reelection in part because the base is energized and the money is rolling in.

Trump campaign spokeswoman Kayleigh McEnany said the campaign brought in 50,000 new donors in two days and raised $15 million in the first three days of the impeachment inquiry — the same amount Biden raised in the last three-month period.

“The American people stand with the president they elected,” she said. “This is backfiring magnificently on the Democrats, and they’re too blinded by their obsession with taking down President Trump to see it.”

The House is moving quickly to investigate and hopes to consider articles of impeachment by the end of the year. On Monday, Democrats subpoenaed documents from the Pentagon and the Office of Management and Budget.

Michael Caputo, a former top adviser to Trump during his first campaign ensnared in the Russia investigation, praised Trump for fighting back against Democrats but said the president was always going to be impeached no matter how small the infraction.

“He is going to be impeached for jaywalking,” Caputo said. “Any mistake the president makes they will impeach him on.”

Darren Samuelsohn contributed to this report.