President Donald Trump on Monday praised a new trade deal struck with Canada and Mexico to revamp NAFTA, but acknowledged he could have trouble getting Congress to approve it if Democrats take control of the House or Senate in the

"I understand the world of politics, I think, as well as anybody," Trump said during a Ross Garden ceremony. "They can take the greatest thing ever done and try to make it sound as bad as possible."

Trump savored the end of 14 months of difficult talks that concluded late Sunday night, portraying the deal as a validation of his trade policies and the negotiating leverage provided by tariffs on Canadian and Mexican steel and aluminum and threatened duties on automotive products.

“By the way, without tariffs, we wouldn’t be talking about a deal. Just for those babies out there who keep talking about tariffs. That includes Congress. ‘Oh, please don’t charge tariffs,'" he said, mimicking those who have expressed concern about his tactics.

Trump said the new U.S.-Mexico-Canada Agreement, or USMCA, would help U.S. workers and companies by increasing incentives to manufacture in the United States and North America. He criticized the existing NAFTA deal, negotiated more than 25 years ago, as “perhaps the worst trade deal ever made.”

Trump also reiterated his threat to “terminate and replace” the existing NAFTA framework, a move that could force reluctant lawmakers to consider the new agreement, even if they decide they prefer the existing pact or want some provisions reworked. It also could set up a clash with Congress over whether Trump has the authority to withdraw from NAFTA.

While some Republicans stepped forward to praise the new agreement, a number of lawmakers in both parties said they were still evaluating the deal.

Democrats are particularly interested in the labor and environment protections contained in the pact, while Republicans have questions about a sunset-review mechanism that could force a renegotiation of the agreement in as little as six years, as well as other provisions that represent a departure from prior trade deals.

The new agreement doesn't remove the U.S. tariffs on steel and aluminum imports from Canada and Mexico, which were also imposed on most trading partners from around the world. Trump said the steel tariffs will remain in place “until such time as we can do something different — like quotas perhaps. We are not going to allow our steel industry to disappear.”

Despite Trump's suggestion that tariff pressure helped bring about the deal, other administrations have negotiated trade deals without threatening import taxes to get countries to the negotiating table. In addition, retaliatory tariffs that Canada and Mexico imposed on U.S. farm goods and other products also will remain in place. That leaves some farmers worse off than they were when the NAFTA renegotiation began.

But, generally, there was a sigh of relief from many in Congress and among business and labor groups that the final pact includes Canada. The Trump administration had struck a deal with Mexico in late August, and Trump had threatened to leave Canada out of the new agreement if a three-way pact could not be struck. Intense negotiations over the last several weeks led to an initial announcement of the three-way agreement on Sunday night.

“The United States benefits when all three countries are held to the high standards laid out in Trade Promotion Authority," House Speaker Paul Ryan said in a statement, referring to legislation that governs negotiations of trade deals. "That’s why I’m pleased that the Trump administration succeeded in bringing Canada into the fold to reach a trilateral agreement. I look forward to reviewing the text of the agreement, particularly the dairy provisions."