Legislating is often described as more art than science, but it’s really just grade-school arithmetic: Bills either have the votes needed to pass, or they don’t.

Republicans have a president in the White House and a numerical majority in Congress—237 seats out of the 430 currently occupied in the House, and 52 out of 100 in the Senate. In theory, that’s enough to run the show. “Welcome to the dawn of a new unified Republican government,” an ebullient House Speaker Paul Ryan declared to reporters the week after the November election.

He was using the word “unified” in a general sense. Republicans now had, in the presidency, the capstone to their decade-long crawl back to power in Washington. But as the last week has made abundantly clear, the idea of unification was wishful thinking, and mostly an illusion. As Ryan and Trump surveyed the results of the elections, they each seemed to see a much bigger victory than the GOP had actually won.

The president described his relatively narrow Electoral College margin—paired with a popular vote loss—as a “massive landslide.” And Ryan moved swiftly to enact a conservative agenda with Republican votes alone. He envisioned a GOP version of the Democrats’ legislative burst in 2009, when President Barack Obama, Speaker Nancy Pelosi, and Senate Majority Leader Harry Reid teamed up to enact a major stimulus bill, the Affordable Care Act, Wall Street reform, and countless other more modest pieces of legislation in under two years.

But there was a big difference between the unified Democratic government of 2009-2010 and the Republican majorities of today: votes. The Democrats simply had many more of them. In the House, Obama’s party controlled at least 255 seats during most of the 111th Congress, and for a seven-month stretch in late 2009, Democrats had 60 votes in the Senate—enough to defeat a GOP filibuster. When the House approved the final version of Obamacare in March 2010, the bill passed despite opposition from 34 Democrats. Republicans could have survived no more than 22 defections on the American Health Care Act last week, and when Ryan withdrew the bill, Trump said the party leadership was about 10 to 15 votes short. In other words, if Republicans had the same number of seats as Democrats did seven years ago, the legislation would have passed.

The failure of the GOP health-care bill has, rather predictably, unleashed a circular firing squad within the party. Ryan blamed the compromise-averse members of the House Freedom Caucus, who in turn blamed the moderates. Conservative activists and Trump loyalists blamed the speaker, while the president is lashing out at just about anyone who didn’t support the bill, including Democrats who were excluded from the process from the beginning.

“The Freedom Caucus will hurt the entire Republican agenda if they don't get on the team, & fast,” Trump tweeted Thursday morning. “We must fight them, & Dems, in 2018!”

If the president is battling both conservatives and Democrats for the next 20 months, who does that leave to pass his agenda? Subtracting the three dozen or so members of the Freedom Caucus leaves Trump with about 200 votes in the House—well short of a 218-vote majority. At other moments in the past week, though, the president has talked about working with Democrats to strike a deal on health care.

That’s not sitting well with Ryan, who is clinging to his dream of a Republican-only agenda, however fast it might be fading. “I worry we’ll push the president into working with Democrats,” the speaker told CBS’s Norah O’Donnell in an interview broadcast Thursday morning. “I don’t want that to happen.”

The bluntness of Ryan’s remark shocked even his fellow Republican, Senator Bob Corker of Tennessee, who responded on Twitter: “We have come a long way in our country when the speaker of one party urges a president NOT to work with the other party to solve a problem.”

The speaker clarified later in the day that his comment was limited to health care and that he was not foreclosing the possibility of bipartisanship altogether. But the exchange underscored that the gulf within the Republican Party is just not about policy, but about governing philosophy. Ryan’s vision of legislating has rarely included Democrats, which is one reason he worked so carefully to craft health-care and tax bills that could circumvent the 60-vote filibuster threshold in the Senate.

That strategy has always been iffy, however, because Republicans have barely enough votes to assemble a simple majority in the upper chamber, let alone a three-fifths supermajority. In the first three months of the new Congress, the Senate has not passed a single piece of significant legislation that was subject to a filibuster. Aside from confirming a couple dozen nominees to Trump’s Cabinet, all Republicans have been able to do is clear resolutions of disapproval under the Congressional Review Act, which by law need only 51 votes to pass.

And even those have been arduous. On Thursday morning, as Ryan was scoffing at the notion of bipartisanship, Senator Johnny Isakson of Georgia was casting his first vote in six weeks across the Capitol. Battling Parkinson’s disease and recovering from two back surgeries, he appeared on the Senate floor with the help of a walker and gave Republicans their 50th vote for a measure that would kill an Obama administration rule prohibiting states from blocking federal grants from going to Planned Parenthood. Two GOP senators supportive of Planned Parenthood, Susan Collins of Maine and Lisa Murkowski of Alaska, had already voted no on the bill, and Vice President Mike Pence was waiting for Isakson so he could cast a tie-breaking vote in favor of the resolution.

It was an unfortunate picture of the Republican congressional majority at the moment—slim and halting, and much shakier than it once seemed.