Barack Obama hit back at fellow Democrats who oppose his trade initiatives on Tuesday, saying they have their facts wrong on the eve of a key Senate vote.

The president’s blunt words came as liberals, labor unions and others stepped up efforts to block his trade proposals, including the Trans-Pacific Partnership, which they say hurt US jobs.

“I would not be doing this trade deal if I did not think it was good for the middle class,” Obama said in an interview with MSNBC. “When you hear folks make a lot of suggestions about how bad this trade deal is, when you dig into the facts, they are wrong.”

Asked particularly about criticisms from Senator Elizabeth Warren, a Democrat, Obama said: “I love Elizabeth. We’re allies on a whole host of issues. But she’s wrong on this.”

But several top Democrats aren’t backing down. Senate minority leader Harry Reid of Nevada told reporters, “I’m not only no, I’m hell no” on Obama’s bid for “fast-track” authority.

The Senate finance committee plans to vote on Wednesday on the fast-track measure. It would renew presidential authority to send Congress trade deals it can endorse or reject, but not amend.

Few issues divide Democrats more than trade. Obama, like former president Bill Clinton, supports free trade, but most Democratic lawmakers do not.

Republicans generally support trade pacts. But Obama can’t count on them alone to push the fiercely debated bills through the Republican-controlled House and Senate.

Clinton’s and Obama’s trade stands – and liberal groups’ opposition – pose a dilemma for Hillary Clinton, the former secretary of state now seeking the presidency. Campaigning on Tuesday in New Hampshire, she declined to say whether she supports the Pacific Rim proposal.

“We need to build things, too,” Clinton said, taking a pro-manufacturing stance generally embraced by both parties. “We have to do our part in making sure we have the capabilities and skills to be competitive,” she said, while getting back to “a much more focused effort, in my opinion, to try to produce those capacities here at home”.

Meanwhile on Tuesday, a Senate finance committee hearing exposed Democratic divisions. Senators including Sherrod Brown of Ohio and Debbie Stabenow reiterated concerns that trade deals help foreign countries more than the US.

Senator Charles Schumer, a Democrat, insisted that the administration press China to stop manipulating its currency, even though China isn’t a party to the Pacific Rim negotiations. “I’m disappointed in the efforts by President Obama,” Schumer said.

If a nation keeps its currency value artificially low, it can boost exports by making local products more affordable to foreigners. Economists disagree on whether China still engages in the practice, and the Obama administration says it addresses currency manipulation in the fast track bill.

Several finance committee Democrats back the bill. Senator Mark Warner said the United States risks being left on the sidelines of an expanding global economy.

“Let’s not miss the opportunity for America to once again reassert its leadership” in trade, Warner said.

The Chamber of Commerce, a business group, strongly endorsed the fast track legislation Tuesday, while the AFL-CIO labor federation denounced it.

Senate approval of fast track seems likely, but the bill’s fate is less certain in the House. House Democrats overwhelmingly oppose it, and some House Republicans are loath to give new authorities to Obama.