Donald Trump has cleared the field of competitors for the Republican nomination but has still not won over one particular, and significant, constituency. Legislators have been curiously resistant to his charms, far more so than those with executive branch experience. While this pattern may have no influence on the outcome of the election, it could turn out to have large implications for the balance of powers should he be elected president.

Trump has received endorsements from others who sought the nomination and their supporters, especially governors or former governors. These include Chris Christie, Bobby Jindal, Rick Perry, Scott Walker, and Nikki Haley. Rounding out the federal executive branch, now Dick Cheney and John Bolton are supporting him. And yet at one point, during the contested part of his campaign, Trump had only one endorsement from a sitting United States senator, Sen. Jeff Sessions of Alabama. That is starting to change now that he is running unopposed, but the cool response from the Senate and an only slightly warmer one from the House—it is hardly even tepid—is striking.

Three people are worth noting. Former Speaker John Boehner called Ted Cruz “Lucifer in the flesh,” and yet still moved slowly in declaring support for Satan’s opponent. Meanwhile, Speaker Paul Ryan is “just not ready” to support him, and Sen. Ben Sasse has openly planted his flag in opposition. Trump won almost every demographic in the primaries except Congressional Republicans. Was Alexander Hamilton right, in Federalist 70, to say that the legislature is “best adapted to deliberation and wisdom?”

Principled opposition to Trump certainly must account for some of the response from Congress, although most observers will be struck by the novelty of finding the words “principled” and “Congress” in the same sentence. Gallup reports that only 8 percent of Americans have “a great deal/quite a lot” of confidence in Congress, as opposed to 28 percent for banks and 72 percent for the military. Congress ranks dead last among all the options given. But whatever the reasons they oppose him, a Trump victory would create an unprecedented relationship between Congress and the Presidency.

It is worth considering what this pattern of opposition from Congressional Republicans might mean for a Trump administration. The first thing to note is the novelty of a modern president lacking the support of his own party in Congress. The opposite has been the trend, with members of Congress becoming more polarized and supporting or opposing the president along party lines. Clio Andris and colleagues have produced a study of voting in the House of Representatives that found the two parties becoming more polarized at a rate of 5 percent a year. The result is that Congress has almost become a parliament, with members acting to implement the agenda of their party leader when that person is president. As a case in point, Harry Reid and Nancy Pelosi probably did more to bring Obamacare into law than the man for whom it is named.

If Trump were to lack a constituency in Congress among members of his own party, the parliamentary dynamic would not work for him. Instead, a President Trump would have to cut a lot of deals—which he says he is good at doing—to get even Republicans to go along. Think of a Hillary Clinton presidency as a contrast. A President Clinton would have the full support of Congressional Democrats while facing the opposition of Republicans, even those Republicans who might have voted for her to keep Trump out of the White House. Partisan polarization would continue and probably get worse. The Democrats would have no interest in opposing her agenda and the Republicans would have no interest in supporting it. The Obama administration has been eight years of exactly this.

But Trump, again, would need to wheel and deal to get anything through Congress, even if the Republicans held a majority. Unlike presidents in the past and, presumably, in the future, he would face opposition from both parties. What might Congressional Republicans get out of him in a deal? For a start, they might be able to regain the status and power that Congress has lost over the last century. Sen. Mike Lee has already joined with other members of Congress (all Republicans) to form the “Article I Project,” an effort to restore Congress to its intended position as “first among the federal government’s three co-equal branches.”

Many conservatives consider the “imperial presidency” to be progressivism’s most destructive legacy. But have any considered that Donald Trump might present the best opportunity in a generation to regain a role for Congress as more than the legislating arm of the executive branch? The irony is that the way to reestablish the balance conservatives have been longing for is to elect a man that Constitutionally-minded conservatives think is, himself, unbalanced. This says less about their assessment of Trump or those who make it than it does about the imperium of the modern presidency.

No modern president has relinquished any powers willingly, or at all, regardless of party, while Congressional majorities of both parties have been willing to cede their powers to the executive of their party. A president opposed by both parties in Congress might reverse or slow this drift. How Congressional Republicans respond to the nomination of Donald Trump will give us an indication of the strength of the currents that have taken the Constitution in a parliamentary direction.

Geoffrey M. Vaughan is associate professor of political science at Assumption College.