WASHINGTON (AP) — With President Donald Trump threatening to slap tariffs on goods from Mexico, his transformation of Republican Party trade policy is nearly complete.

Republican lawmakers usually don't like tariffs. They're viewed as a tax on consumers and unwanted government intervention in free trade. But many Republicans, unwilling to buck Trump, are prepared to follow the president's lead and support 5% tariffs on Mexico in his dispute over illegal immigration .

It's a crossroads for the GOP as the White House is taking the party in a confrontational new direction. The tariffs may, or may not, solve the border crisis. But as with Trump's tariffs on imports of steel and aluminum and goods from China, the threat alone sending ripple effects into a jittery economy.

"I'm a free trader but I want equal access," said Georgia GOP Sen. David Perdue, a former Fortune 500 business executive and close ally of Trump.

"What we're talking about here is trying to change behavior," he said. "Here, we need the Mexican government to help us with this avalanche of people that's coming."

Said Florida GOP Sen. Rick Scott, "I don't like it, but I'm going to support the president... I want border security."

As Trump returned Friday from Europe, he was expected to assess the situation ahead Monday's deadline for imposing the tariffs. Talks between U.S. and Mexican officials were underway all week.

Trump tweeted from aboard Air Force One there was "a good chance" a deal could be struck. But he said: "If we are unable to make the deal, Mexico will begin paying Tariffs at the 5% level on Monday!"

The administration says Mexico can prevent the tariffs by securing its southern border with Guatemala, cracking down on criminal smuggling organizations and overhauling its asylum system. But it's unclear if any of the concessions so far will satisfy the president.

During negotiations in Washington, Mexican officials have agreed to deploy 6,000 National Guard troops to the Mexican border with Guatemala to help control the flow of migrants. However, one of the U.S.'s main demands, that Mexico agree to becoming a "safe third country" for asylum seekers, remained a key topic during Friday's talks, those monitoring the situation said. Mexico has resisted that demand, which would make it difficult for those who enter Mexico from other countries to claim asylum in the U.S.

"That is being looked at," Mexican President Andrés Manuel López Obrador said Friday during his daily news conference, where he held out hope there was still time before Monday to strike a deal. "I am optimistic that an agreement will be reached."

The debate is catapulting Republican lawmakers into new terrain, using tariffs not only as economic policy for trading outcomes but as a negotiating tool in an unrelated dispute over immigration policy. The tactic runs counter to long-held GOP views on trade — prioritizing free markets — and is pushing Republicans, particularly those who will be running for re-election alongside Trump in 2020, to fall in line.

Sen. Thom Tillis of North Carolina said he was prepared to support Trump if the issue comes to a vote. But he also hopes any tariffs are temporary — and don't dramatically escalate.

"None of us would want to see a long-term tariff imposed," Tillis said. "I think it's fair to put it on the table. If it was a 50% tariff we'd be having a different discussion."

Ever since President Ronald Reagan, there has been an "inexorable movement" within the GOP toward free trade, culminating in passage of the North American Free Trade Agreement, or NAFTA, said Tim Phillips, president of Americans for Prosperity, a pro-free market group backed by the Koch enterprise.

But that's changing under Trump, and it's scrambling traditional alliances between Republican lawmakers and America's business community, putting both on uncertain footing. Trump wants to do away with NAFTA — the new U.S.-Mexico-Canada deal had been heading toward a vote in Congress but could be jeopardized by the tariffs — and he has shelved the Obama-era proposed Trans-Pacific Partnership with more than a dozen nations.

"We've got a long road ahead of us to bring that orthodoxy back," Phillips said.

To be sure, plenty of Republicans are resisting Trump's transformation. Those from agricultural, manufacturing and border states are particularly opposed to the tariffs on Mexico. Kansas GOP Sen. Pat Roberts called tariffs "a really awkward thing. And tariffs are like shattered glass. You never know where it's going to end."

In some ways, Trump's approach is more in line with liberals, including potential 2020 rivals Bernie Sanders and Elizabeth Warren, creating new political cross currents in the debate.

The U.S. Chamber of Commerce, long the dominant business group in Washington, has been encouraging the White House and Republican lawmakers to steer away from the Mexico tariffs. The group is evaluating legal options to intervene if they are put in place.

"We do have a real crisis at the border," said Neil Bradley, the Chamber's chief policy officer. "But imposing a tax that's going to be paid for by businesses and consumers won't solve that problem — and if anything will make it worse."

With Friday's jobs numbers pointing to a slowing economy, Bradley said the administration needs to avoid missteps. "Imposing tariffs on everything we import from our No. 1 trading partner would definitely count as a misstep," he said.

At the same time, it's not at all clear the tariffs would check the rising number of migrants at the border, a crisis that has vexed the White House. The Department of Homeland Security said this week that U.S. apprehensions of migrants illegally crossing the border in May hit the highest level in more than a decade: 132,887.

Frank Sharry, executive director of the advocacy group America's Voice, said Trump is taking a "sledgehammer" to a complex migration and refugee problem, which stems from conditions in Central America and is fueled by smugglers capitalizing on the president's own threats to shut the U.S.-Mexican border.

"This is a regional refugee crisis caused by violence and drought in Central America that has been so thoroughly mismanaged by the failing and flailing Trump administration that they've created a humanitarian crisis at our border," he said. Trump, he said, is "quadrupling down on a failed strategy."

Warning Trump off the tariffs, some GOP senators have pledged to vote against them in a measure of disapproval that would send a stiff rebuke from his own party.

But Senate Majority Leader Mitch McConnell has not promised to bring a vote forward, and others monitoring the situation doubt he ever will.

And that may be fine with many lawmakers, too. GOP Sen. Josh Hawley of Missouri said he understands the president's frustrations and is willing to consider options.

"You've got to fight the fight differently," he said. "It doesn't necessarily mean you're against free trade. It just means you got to take the long view of what free trade looks like."

___

Associated Press writers Jill Colvin, Matthew Lee and Luis Alonso Lugo in Washington contributed to this report.