The House’s top Republican and Democrat switched normal roles during the “fast-track” debate, with President Barack Obama relying on the GOP, rather than his own party, to carry his trade package across the finish line.

But when it comes to the president’s nuclear agreement with Iran, it’s back to normal for Speaker John A. Boehner and Minority Leader Nancy Pelosi: She’s backing Obama, he isn’t.

Pelosi, D-Calif., announced Thursday she will be strongly urging her members to support the agreement, which would subject Iran to frequent inspections and shrink the Islamic republic’s uranium stockpile to well below the levels needed for a weapon for 15 years.

“The president has been very clear: A nuclear Iran is not acceptable to the United States, to the world and in particular to Israel,” Pelosi said at her weekly news conference. “This agreement is precisely about intensifying our vigilance.”

Pelosi Will Lobby Democrats to Back Iran Deal

Waving the 80-page document in the air for a perfect photo opportunity, Pelosi added, “I made it very clear to [House Democrats] my own standing on this issue and why this is a good agreement.”

When the agreement was announced Tuesday, Pelosi signaled her enthusiasm for what she called a “historic” accord, negotiated by Obama, cabinet secretaries and an international coalition.

Thursday’s remarks to reporters provided the first indication that she would be a surrogate for the Obama administration in lining up Democrats’ support on Capitol Hill. It’s a significant development for the White House, which watched Pelosi empower her members to reject Trade Promotion Authority legislation last month despite the president’s pleas.

Though most Democrats are inclined to back Obama on the deal, some are on the fence, particularly those with strong allegiances to Israel, which wants Congress to impose tougher sanctions on Iran. Obama is eagerly making members of his administration available to lobby lawmakers and answer questions, with Vice President Joseph R. Biden Jr. already making visits to Capitol Hill to lobby Democrats.

Meanwhile, Boehner, who helped get Republicans to pass Obama’s trade agenda last month, turned on the administration Thursday in the second set of public remarks he’s had a chance to deliver on the subject since Tuesday.

“President Obama says it’s this deal or war. Well, that’s a false choice,” Boehner said at his own news conference. “The sanctions were working, and bringing Iran to its knees. We’re going to continue to review this, but we’re going to fight a bad deal that’s wrong for our national security and wrong for our country.”

Boehner: Obama Presenting ‘False Choice’ on Iran

Under legislation passed by Congress earlier this year, the legislative branch has 60 days to approve or disapprove of the deal, though Obama has pledged to veto any measure blocking his ability to carry out the terms of the agreement.

Boehner said Thursday he wasn’t optimistic the GOP-controlled Congress would provide Obama with the green light to plow ahead.

“Every member of Congress is going to have to make a decision,” said Boehner. “But it’s pretty clear to me the majority of the House and Senate, at a minimum, are opposed to this deal and what those numbers look like … We’ll see.”

Preceding Boehner’s assessment of the state of play, Pelosi told reporters she thought House Democrats at least would be able to sustain a veto.

“We’re in a very positive place,” Pelosi said of her members and where they fell along the spectrum of support.

See photos, follies, HOH Hits and Misses and more at Roll Call’s new video site.

Get breaking news alerts and more from Roll Call in your inbox or on your iPhone.