When Trump occasionally deviates from conservative orthodoxy — or otherwise bucks the party’s consensus — Republican lawmakers try to push him back in line. Earlier this year, Senate Republicans didn’t hesitate to challenge the administration on its plan to impose a 5 percent tariff on all goods imported from Mexico. “I will yield to nobody in passion and seriousness and commitment for securing the border,” Senator Ted Cruz of Texas said to reporters at the time. “But there’s no reason for Texas farmers and ranchers and manufacturers and small businesses to pay the price of massive new taxes.”

Likewise, Senate Republicans took a collective stand against Trump after the White House announced his plan this week to withdraw American forces from northern Syria, clearing the path for Turkish military operations against Kurds in the region. Mitch McConnell, the majority leader, warned Trump against a “precipitous withdrawal”; Lindsey Graham of South Carolina called the move “a big win for Iran and Assad , a big win for ISIS”; Ben Sasse of Nebraska said the president “needs to know that this bad decision will likely result in the slaughter of allies who fought with us, including women and children.”

It’s true that the Republican base isn’t invested in American foreign policy toward Syria. It’s also true, however, that Trump may well lash out against his Republican critics, which could turn his voters against them on this particular issue. But Senate Republicans spoke right up. This time around, the fear that’s supposed to drive their acquiescence to Trump doesn’t exist.

If Republicans are willing to challenge Trump on his foreign policy, including the disposition of American troops abroad, then the difference when it comes to Ukraine — as well as other scandals, like the president’s continued corruption and self-dealing — may just be that they don’t see a problem. You can read Senator Marco Rubio’s willingness to downplay Trump’s open call to intervene in the 2020 election as a craven surrender, or you can take it at face value: Maybe Rubio just doesn’t think it’s that big of a deal.

None of this would be out of character for congressional Republicans. These are the lawmakers who refused to fix the Voting Rights Act after the Supreme Court killed a key provision of the law in 2013. They said nothing when Trump tried to launch a crusade against imaginary “voter fraud.” They are at best indifferent to the restrictive laws and voter purges that keep millions of Americans from the polls.

Sometimes, the simplest answer is the correct one. Why are most Republicans silent in the face of the president’s attempt to cheat his way to re-election? Perhaps it’s because they don’t think it’s wrong — or because they don’t care if it is.