If Democrats in Congress thought they could count on even occasional Republican help in stymieing President Trump’s agenda, they have been disappointed so far. Senate Republicans have voted en masse for Trump’s Cabinet nominees. Likewise, any Republicans in the Senate who were hoping for the occasional Democratic vote have been similarly let down. Senate Democrats have opposed Trump’s picks in record numbers. The same is happening in the House. Republicans in that chamber are voting in lockstep with the Trump administration, while Democrats are almost universally voting in opposition. Indeed, both House caucuses are more unified and polarized than they have been in at least 60 years.

The average House Republican has voted in line with Trump’s position more than 98 percent of the time during the first 19 days of the administration. Now, some caution is warranted — that percentage is based on only 12 votes. Things could change. Still, if Republicans continue to back Trump so uniformly for the rest of 2017, they’ll notch the highest rate of support by House members from the president’s party for any year since at least 1953. Over that time, House members from the president’s party have voted in agreement with the president 72 percent of the time, on average.

That percentage has increased in recent years along with polarization. From 2009 to 2016, for instance, House Democrats voted with President Obama 86 percent of the time, on average. That’s still lower than the level exhibited by House Republicans in the first weeks of the Trump presidency.

What’s causing the record level of support for Trump among Republicans? Well, House Republicans may simply agree with Trump — at least on the issues to come before the chamber so far. On the other hand, Republican lawmakers may fear that Trump will lash out against them — (see McCain, John) — or that opposing him could lead to a primary challenge. Whatever the cause, House Republicans don’t seem to think that voting with Trump will hurt their re-election chances. No Republican in Congress has voted with Trump less than 50 percent of the time. Back in 2008 by comparison, House Republicans were worried President George W. Bush’s unpopularity would cost them re-election, and the average GOP House member voted with him just 68 percent of the time. This year, even GOP House members from districts won by Hillary Clinton are voting with Trump. Republican Reps. Ryan Costello of Pennsylvania, Leonard Lance of New Jersey, and Dana Rohrabacher and David Valadao of California, for example, all represent districts that Clinton won, and each has voted with Trump at least 90 percent of the time.

Democrats, meanwhile, are under tremendous pressure from their base to oppose Trump. And that pressure appears to be working. House Democrats have, on average, voted with Trump just 3 percent of the time. From 1953 to 2016, the average House member from the major party that did not hold the White House voted with the president 34 percent of the time. That number has dropped as polarization has increased, but if the rest of this year plays out like the first few weeks have, it’ll be the lowest since 1953. Even during the Obama years, when the GOP seemed to oppose everything he did, House Republicans each year voted with the president at least 8 percent of the time — and frequently more often. More than 75 percent of House Democrats have voted with Trump 0 percent of the time.

The unified Democratic front has a few plausible explanations. Democrats are probably worried more about a primary challenge than a general-election defeat. There are only 12 districts that both were won by Trump and are represented by a Democrat in the House. Also, there are few moderate Democrats who might vote with Trump. That’s because competitive districts are more likely to be represented by moderates, and there are very few of those districts now.

What does seem clear, at least so far, is that Trump’s unusual mix of policy positions has not resulted in the blurring of partisan lines in Washington. He is not, as some hoped or thought he would be, a “No Labels” president. Trump has merely exacerbated the trend of Democrats and Republicans agreeing on pretty much nothing.