Seeking to build support among his fellow Republicans for a key trade pact, Donald Trump will meet privately Thursday afternoon with Republican senators. And fireworks are possible if the president refuses to drop his tariffs on two U.S. neighbors despite GOP pleas and threats.

The White House has yet to submit to Congress a revised version of the North American Free Trade Agreement, which Trump’s top trade advisers negotiated with Mexico and Canada amid a litany of presidential demands and threats toward two longtime U.S. allies.

A White House official described the 2:30 p.m. session as a “broad” discussion about a range of trade-related matters. But Trump and his team need to shore up GOP support of the U.S.-Mexico-Canada Agreement to shield the president from what would be a major embarrassment if Congress rejects the pact.

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Here are three things to watch when the president huddles with Senate Republicans.

GOP tariff tussle

The Roosevelt Room session will put Trump face-to-face with Republican senators who are boiling mad with his refusal to drop steel and aluminum tariffs on America’s neighbors.

One will be influential Senate Finance Chairman Charles E. Grassley of Iowa, who penned a blunt Wall Street Journal op-ed Monday with this headline despite his support for the pact: “Trump’s Tariffs End or His Trade Deal Dies.”

“These levies (tariffs) are a tax on Americans, and they jeopardize USMCA’s prospects of passage in the Mexican Congress, Canadian Parliament and U.S. Congress,” wrote the chairman, saying he has talked with his own colleagues and officials from both countries about the matter. “Canadian and Mexican trade officials may be more delicate in their language, but they’re diplomats. I’m not. If these tariffs aren’t lifted, USMCA is dead. There is no appetite in Congress to debate USMCA with these tariffs in place.”

Grassley told the world how he really feels, as usual. How will Trump react to any such candid talk?

Crammed calendar

The White House has yet to submit the three-country agreement to Congress, meaning lawmakers and aides have not had a chance to read the fine print, hold hearings and debate whether it meets the muster of enough members of both chambers.

That will take time. Months, probably. It may only be May 1, but spare time is not something either chamber has a lot of.

In the Senate, Majority Leader Mitch McConnell, R-Ky., has pledged to continue churning through Trump’s judicial nominees and picks for Cabinet-level and other senior department posts. With Democrats insisting on slowing those processes as much as they can, that doesn’t leave a ton of floor time for a major spending pact — especially since McConnell is an appropriator at heart, and also has promised to move spending bills on the floor later this year.

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And over in the House, its new Democratic leadership is balancing 2020 messaging bills — like ones expected this month to shore up the 2010 health care law, lower prescription drug prices and provide disaster relief, according to Majority Leader Steny H. Hoyer of Maryland. And then June is appropriations month, Hoyer said recently, also suggesting a flood insurance extension could be forthcoming around that time.

Devoid of Democrats

The White House official confirmed there will be no members of the opposition party at the Thursday meeting. But the president will need some Democrats in the House and, as things stand now, likely the Senate.

Perhaps that’s why Trump brought up trade at an Oval Office meeting Monday with top Democrats that mostly focused on a potential infrastructure package.

It was Trump who brought up the U.S.-Mexico-Canada pact with the Democrats, even having his staff “note that legislation in the Mexican legislature had advanced addressing the concerns of Democrats,” according to a senior Democratic aide.

Likely sensing leverage, Speaker Nancy Pelosi, D-Calif., then told the president that her members would need to be made confident that the pact is enforceable, saying “enforcement “ and “implementation” of the agreement’s provisions — particularly in Mexico — would be “essential.”

On Thursday, the speaker’s comments offered a succinct assessment of the agreement’s status on Capitol Hill.

“Yes, we would like to get to yes,” she told reporters. “I thought it would be easier than this because we have been clear about enforcement in any trade agreement.”

Lindsey McPherson contributed to this report.