Republican presidential candidate Donald Trump held a rally in Eugene, Ore., on May 6. "I’m no fan of Bernie Sanders, but he is 100 percent right," he said. "Hillary Clinton is totally controlled by the people that put up her money." (Reuters)

At a campaign rally here in one of the most liberal towns in America, Donald Trump offered praise for an ­unusual party: avowed democratic socialist Bernie Sanders.

“Now, I’m no fan of Bernie Sanders, but he is 100 percent right,” Trump told a crowd here this weekend. “He is 100 percent right: Hillary Clinton is totally controlled by the people that put up her money. She’s totally controlled by Wall Street.”

That’s not the only area where the presumptive Republican nominee sounds like Sanders, who is challenging Clinton for the Democratic nomination. On a series of issues, including free trade and foreign military intervention, Trump is effectively running to the left not only of his own party but also of Clinton.

For weeks, Trump has openly praised Sanders, crediting the senator from Vermont for raising questions about the former secretary of state’s judgment on campaign finance, trade and foreign policy. He has also pointed to Sanders’s questioning of Clinton’s qualifications as a sign that the topic is fair game.

“NAFTA has been one of the great economic disasters. Who signed it? Clinton. Clinton,” Trump said Saturday at a rally in Lynden, Wash. He was referring to the North American Free Trade Agreement, which was actually signed by George H.W. Bush but was implemented through legislation signed by Bill Clinton.

Former Secretary of State Hillary Clinton speaks to and meets California voters during a rally at East Los Angeles College in east Los Angeles on Thursday May 5, 2016. (Melina Mara/The Washington Post)

“It has destroyed, I’ll tell you what, it’s destroyed our country as we know it,” Trump said.

The line of attack poses an unusual and vexing challenge for the Democratic front-runner, who has spent months embracing increasingly liberal positions in her primary fight with Sanders. After jockeying to win over voters on the left, the Clinton campaign is now tasked with pinpointing the best way to attack Trump — an ideological moving target who sometimes switches positions within the space of a day — while also reaching out to moderates and disaffected conservatives.

The real estate mogul has sought to develop a clear contrast with Clinton on foreign affairs and international trade, calling for an “America First” policy that simultaneously turns her experience as the nation’s chief diplomat against her while tapping into the anxieties of angry voters worried about being left behind by globalization. In recent days, he has also moved to the left on the minimum wage and tax policy, suggesting that he is willing to alter his positions to benefit the middle class.

But Trump’s populist pitch may be seriously hampered, even among voters skeptical of Clinton, by his controversial statements on women, Muslims and Mexican immigrants.

During an anti-Trump protest in Eugene last week, many said they would remain firmly opposed to his candidacy on the basis of social issues, including his controversial calls to deport millions of illegal immigrants and to temporarily ban Muslim foreigners from entering the country.

Doug Gustafson, 29, of Bellingham, Wash., is a Sanders supporter who agrees that both Sanders and Trump have ignited the passions of Americans who feel increasingly disenfranchised. But although he agrees with Trump that recent trade pacts are bad for American workers, Gustafson said the Republican’s controversial rhetoric disqualifies him from consideration for higher office.

“I think a broken clock is right twice a day,” he said.

But Gustafson added that, given her cozy ties to Wall Street, he would not be able to vote for Clinton in November, either. “I’m not going to vote for the oligarchy,” he said.

Not every Sanders supporter is “Bernie or Bust,” however.

“She’s not an infallible candidate or human being, but she’ll have my support in the general,” said Andy Brocco, 44, who lives in Eugene and is supporting Sanders.

Brianna Soumokil, 19, called herself a “big Bernie supporter” but said that she would vote for Clinton in the general election “just to ensure Trump doesn’t get it.”

She dismissed Trump’s praise of Sanders for attacking Clinton. “I would definitely not be happy voting for her. I don’t support her. I don’t believe in what she believes in,” Soumokil said. “But when it comes down to the same-old-same-old or fascism, I’d definitely choose Hillary.”

Sanders has also made clear he is no fan of Trump, but the two do broadly agree on some issues, at least when it comes to their critiques.

Like Trump, Sanders has regularly warned about what he believes are the lopsided benefits of global trade deals, including the Trans-Pacific Partnership, which was brokered by the Obama administration. Clinton praised the deal while she was secretary of state, but after heavy attacks from Sanders last year, she said she opposes the pact.

Sanders and Trump have both blasted Clinton for her 2003 vote in favor of the Iraq War, for her ties to wealthy Wall Street donors and over her qualifications to be president. Both also now criticize her for the 2011 military intervention in Libya, although Trump was a strong supporter of it at the time.

“He’s been tough on her. In fact, I’d like him to keep going because the longer he goes, the more I’m going to like it,” Trump said last month in Harrisburg, Pa., the first of many such comments. “So Bernie Sanders, not me, said she is not qualified. So now I’m going to say, ‘She’s not qualified.’ Okay?”

Sanders’s aides dismiss suggestions that Trump cribbing the senator’s words will ultimately hurt Clinton. They argue that these lines of attack pale in comparison to the thick books of opposition research that Republicans will employ against her.

Trump’s apparent positions of agreement with Sanders have added to his problems with Republicans, many of whom are refusing to back him as the presumptive nominee because of his caustic rhetoric and controversial policies. The mogul waves away such complaints.

“Some people would say I’m not that conservative on trade,” he said this weekend in Eugene. “And I believe in free trade, which everybody likes, but we’ve been taken advantage of by globalization because we have leaders that are incompetent. They don’t know how to do deals.”

He added on ABC’s “This Week”: “Don’t forget — this is called the Republican Party. It’s not called the Conservative Party.”

As for Clinton, she and her campaign have gone hard after Trump since he effectively secured the GOP nomination last week, attacking him as an intolerant, out-of-touch plutocrat. She has focused in particular on some of his more bellicose foreign policy remarks as perilous and unsafe.

“What I’m hearing from him talk about, ‘Oh, let other countries have nuclear weapons.’ . . . We’re trying to reduce their numbers to prevent other countries from having them, and he talks about it like it’s some real estate deal,” Clinton said Friday in Oakland, Calif. “That is dangerous. It is reckless.”

Scott Clement and Anne Gearan in Washington and Katie Zezima in Oakland, Calif., contributed to this report.