A majority of Republicans support President Trump's policy of separating families crossing the U.S.-Mexico border, according to recent polls. But some key Republicans in Congress don't. Does that mean Trump is losing his support in Congress for one of his most controversial policies?

Republican leaders have been struggling for years to find a home on immigration. After a consensus by party elites in 2012 that they needed to soften their positions to win over Hispanic voters, Trump pulled them to the right in 2016.

Now that Trump is carrying out his campaign promises to get tough on all immigrants who cross the border, legally or illegally, Republican leaders seem increasingly anxious about it.

Here's a closer look at the Republican factions emerging from the administration's hard line on immigration.

1. The lawmakers who love Trump's zero-tolerance policy

Rep. Steve King (R-Iowa). (Justin Hayworth/AP)

Who's in this group: Mostly House Republicans who also support cutting legal immigration, not just ending illegal immigration. They consider any path to citizenship for undocumented immigrants “amnesty,” even if those immigrants were brought to the country illegally as children.

What they're saying: They echo the Trump administration's main talking points that taking children away from their parents is a deterrent for border-crossers who bring children with them specifically to receive leniency once in the United States.

And they have their own talking points, mainly that the detention centers for children — some of which put use cages, reporters have said — aren't that bad. “These are children that are cared for with better care than they get in their home country,” Rep. Steve King (R-Iowa) told TMZ recently. King has a history of making racially insensitive remarks about immigrants.

Trump's attorney general, Jeff Sessions, is part of this group, too. He recently quoted the Bible to defend “orderly and lawful processes.”

2. The silent majority

Who's in this group: The vast majority of congressional Republicans. Like nearly every controversy enveloping Trump, they'd rather keep their heads down and their mouths shut than risk a confrontation with the person who has shown remarkable influence over Republican base voters.

What they're saying: Well, not much. What they're probably doing is looking at the polls to see what their most reliable voters back home think of all this.

A Quinnipiac University poll out Monday found that 55 percent of Republican voters support family separation, even though two-thirds of the country doesn't.

By that measure, we can expect these lawmakers to try to hold their silence on family separation, even if they don't agree with it.

3. The lawmakers dipping their toes into criticizing Trump

Who's in this group: Republicans who don't agree with family separation but are taking a cautious approach in their criticism of it. These candidates and lawmakers are often walking a tightrope: They may be running for office in bluer states or may need Trump's support to help rally his loyal voters to the polls.

What they're saying: They are criticizing Trump, but with lots of nuance. Sen. Dean Heller (R-Nev.), one of the most endangered senators in November's elections, is a good example. “I do not like the policy,” he said a few weeks ago when local reporters asked him. Through a spokesman, he repeated that he doesn't want children and their parents to be separated, but he also reiterated Trump's talking point that it's Congress's job, not the president's, to end it.

It's the same situation with Rep. Kevin Cramer (R-N.D.), who is running for Senate and wants to stay on Trump's good side.

You could argue that Senate Majority Leader Mitch McConnell (R-Ky.) belongs in this category, too. He made clear Tuesday that all Senate Republicans oppose Trump's family-separation policy. But rather than call on Trump to end it, which he could, he's focused on trying to pass legislation.

4. The full-throated critics

Sen. Ted Cruz (R-Tex.). (Chip Somodevilla/Getty Images)

Who's in this group: This is the most fascinating group because the lawmakers here defy categorization. They include the usual GOP Trump antagonists — Sens. Jeff Flake (Ariz.), John McCain (Ariz.), Ben Sasse (Neb.) and Susan Collins (Maine).

But some of Trump's allies and some conservative leaders are also using strong language to slam the policy and directly confront the president.

What they're saying: Sen. Ted Cruz (Tex.), who's facing a potentially competitive Democratic challenger in November, said he's introducing a bill to keep families together at the border. “All Americans are rightly horrified by the images we are seeing on the news, children in tears pulled away from their mothers and fathers. This must stop. Now,” he said in a statement.

Sen. Orrin G. Hatch (Utah), a Trump ally on taxes, called out the president's inaccurate claim that Congress is the branch of government with the authority to end separations. “The White House can fix it if they want to. I don’t think there’s any question about that,” Hatch said.

And in the clearest sign yet that Trump may be losing his GOP support in Congress, the Senate's No. 2, Sen. John Cornyn (R-Tex.), is also introducing legislation to end family separation. “To the greatest extent possible, families presenting at ports of entry or apprehended crossing the border illegally will be kept together while waiting for their court hearings,” Cornyn said on the Senate floor Monday.

McConnell and Cornyn say they want something passed in the Senate to end family separations by the end of this week.