File this under “Only in Washington”: After Congress passes a spending bill by midnight Friday, lawmakers will be pretty much done working for the year. And, yes, it's only March.

The reason we shouldn't expect any more major legislation to be passed in 2018 can be summed up in two words: direction and election. Specifically, a lack of the first and the existence of the second.

Republicans don't have a consensus on the next big thing on their to-do list, and they're running out of time to figure one out. But even if they suddenly decided they wanted to make a push for welfare reform or another attempt to hack at the Affordable Care Act, they would have a hard time getting it done with the November midterm elections approaching. It's nearly impossible to force lawmakers to take politically tough votes when their jobs could be on the line.

Heck, corralling enough Republicans to pass major legislation was challenging enough for party leaders in a non-election year. Last spring, Republicans fell short by one vote to do something they all campaigned on doing. But repealing the ACA turned out to be easier said than done: Every lawmaker had different ideas about how to go about it, and a number of moderate Republicans got cold feet about the idea of undoing a law on which their constituents relied.

The Senate GOP health care bill failed after three Republicans voted against it (The Washington Post)

This winter, Republican leaders passed a tax system overhaul only by reminding their colleagues of the health-care failure and that another failure was not an option. If Republicans wanted to keep their power beyond 2018, GOP leaders argued to reluctant rank-and-file members, they needed to vote for this tax bill. That, plus a little bit of “cajoling, threats and concessions,” as my colleagues described it, is what got Republicans their only major legislative accomplishment for the year.

As a result of their success, Congress isn't coming up on another one of this legislative and political cliffs. Republicans have their tax bill, and Republicans are content to campaign on that. (Whether that strategy works is to be determined.)

Molly Reynolds, a congressional expert with the Brookings Institution, said there are also no major deadlines coming up that could force Congress to act. Trump's self-imposed deadline for undocumented immigrants known as “dreamers” got nullified by court cases. No major programs need to be reauthorized until late summer and fall, and Congress can easily kick the can down the road on those. The Senate can keep itself busy by approving nominees to Trump's administration. There's just not a lot for them to do. 

As you've probably noticed, we've been talking only about Republican votes on Republican priorities. There's a reason for that. Republicans have largely gone it alone this past year, forsaking any attempt to win over Democrats on health care and taxes. Democrats complain that they were locked out of the process; Republicans say Democrats refused to come to the table.

Whatever the reason, the net effect for Republicans is that they've simply had fewer votes to work with to pass their priorities, and that put an even greater emphasis on cajoling members of their own party to vote a certain way.

That partisan approach to legislating isn't likely to change in 2018. There are a few things on which — in theory — a majority of Democrats and Republicans agree. They want to protect dreamers from deportation, and they want to rebuild crumbling infrastructure. But any broad agreement usually quickly deteriorates when you get into the details.

As we've seen with the immigration fight and its latest iteration this week, Trump is simply an unreliable negotiator, which is the final reason Congress is almost certainly done legislating in a major way this year. He often says what he thinks lawmakers want to hear at the time, then he reneges a few days or sometimes even hours later. He also doesn't seem to have a clear grasp of any of the major issues Congress is debating, which expounds lawmakers' confusion about where he stands.

President Trump on Feb. 28 told Sens. Patrick J. Toomey (R-Pa.) and Joe Manchin III (D-W.Va.) that they are “afraid of the NRA.” (The Washington Post)

Both Democrats and Republicans have said they don't trust Trump to pick a position and stick with it. For 2018, that means they're unlikely to take a risk on a major legislative item that could backfire on them months before an election because their finicky president changes his mind.

What happens in that election could stretch this legislative drought from one year to several years.

Republicans are at risk of losing control of the House in November, and if things go really badly for them, they will lose the Senate, too. Let's say the likeliest of those happens, and come January, Democrats control the House. Then it's an open question whether Congress passes any major legislation for the next few years (besides keeping the government open). We'd basically have the final six years of the Obama administration in reverse: One party in control of at least one chamber of Congress, another in the White House, and a stalemate on pretty much everything until the next big power change.