WASHINGTON, D.C. - The tariffs removed last week by the White House – 25 percent on imported steel and 10 percent on imported aluminum – have disappeared, at least for now. It’s a welcome sign on Capitol Hill, especially for U.S. Sen. Pat Toomey.

“It’s great news that the taxes that Americans had to pay on Canadian and Mexican steel and aluminum have gone away,” the Pennsylvania Republican said.

Toomey had been pushing the Trump administration for months to repeal those tariffs. The move clears a major hurdle for the President as he attempts to pass the United States-Mexico-Canada trade pact.

But now a new set of challenges face the trade deal, which Trump and leaders of Canada and Mexico signed in Nov. 2018. President Trump sent a letter to top Democrats ahead of a White House meeting Wednesday telling them he won’t work on infrastructure – an issue both sides appeared to be willing to work on three weeks ago – until the trade deal is done.

Now, infrastructure appears to be on hold, after House Speaker Nancy Pelosi (D-Calif.) accused the President of engaging in a cover-up stemming from the Mueller report. Trump then offered something of an ultimatum to the Democrats during a fiery news conference in the Rose Garden Wednesday morning: either work with him by ending the investigations or nothing gets done.

“You can’t do it under these circumstances, so get these phony investigations over with,” Trump said.

“He just took a pass, and it makes me wonder why he did that,” Pelosi said during a news conference with Senate Minority Leader Chuck Schumer and several other top Democrats.

Lifting the tariffs is expected to help the auto industry in the short term. But finalizing this trade deal requires Congressional approval, notably from the Democratic-controlled House of Representatives; and aside from the even bigger challenges Trump now faces with House Democrats, he must also get Senate Republicans on-board whenever these talks resume.

“There are still a lot of problems,” Toomey said. “I have serious reservations and concerns about what they have negotiated here.”

Among Toomey’s concerns: how long the deal will last, wage requirements and quotas on products like automobiles, steel, and aluminum, according to a spokesman.

Some trade and industry advocacy groups have expressed their support for the USMCA now that the tariffs are lifted.

“We absolutely think removing the Section 232 tariffs in North America will help pave the way for the ratification of USMCA in all three countries,” said Matt Meenan, a spokesman for the Aluminum Association. “With the tariffs removed, the aluminum industry can now support, without reservations, the passage of USMCA.”