President Donald Trump can veto a resolution blocking his border emergency declaration. If it clears the Republican-led Senate on Thursday, Democrats lack the votes to override him.
But the episode shows again what the 2018 midterm elections brought the GOP: constant pressure.
Democratic control of the House won't produce much legislation in a divided Washington, but it has already produced a fundamental shift in political leverage.
During the first half of Trump's term, Republicans at both ends of Pennsylvania Avenue protected each other. Congress shielded the president from oversight; House and Senate leaders shielded their members from casting politically perilous votes.
The shift in White House accountability has attracted the most attention so far, for good reason. The House Intelligence, Financial Services, Oversight and Judiciary committees have piled overlapping probes of their own onto investigations by prosecutors for special counsel Robert Mueller, the Southern District of New York, the state of New York and the Manhattan district attorney.
Those House initiatives alone could effectively cripple the administration over the next two years. Through the impeachment process, they could even cut it short.
Speaker Nancy Pelosi has signaled the House may ultimately eschew an impeachment battle as divisive and politically counterproductive. But she has the ability to regularly squeeze Trump and his fellow Republicans under any scenario.
Pelosi's gavel lets her force votes on issues where Republican orthodoxy stands at odds with broader public opinion. That includes climate change, gun control measures and higher taxes on the rich.
Pelosi can also force votes on popular issues that divide the GOP while uniting, at least rhetorically, Democrats and the White House. Her legislative agenda includes two 2016 Trump campaign priorities – a costly infrastructure program and action to cut the prices pharmaceutical companies charge – that Republican leaders disdain.
Even if none of those measures wins so much as a Senate floor vote, they create a record for Democratic candidates in 2020 campaigns for Congress and the White House alike.
Power also creates burdens for Democrats. Far more than in 2017-18, the party will share responsibility with Trump and the GOP for events in Washington that so often repel rank-and-file voters.
When comments by freshman Democratic Rep. Ilhan Omar drew bipartisan denunciations of anti-Semitism, House leaders had no choice but to respond. Republicans eventually reclaimed a share of opprobrium for themselves when 23 GOP members voted against a resolution condemning bigotry of all kinds that Democrats unanimously supported.
Democrats began reaping political dividends immediately after winning their House majority last November. With undivided GOP control about to run out, Trump pressed his demand for border wall funding that Republicans earlier sidetracked.
When rebellious conservatives rejected a short-term deal by GOP leaders, Trump rejected it, too. So then-Speaker Paul Ryan refused to allow a vote, triggering the partial government shutdown.
Succeeding Ryan in January, Pelosi forced Trump to surrender unconditionally. That in turn produced the Trump emergency declaration before the Senate on Thursday.
Senators have to vote on it because the law governing emergency declarations requires it once a resolution of disapproval passes the House. Senate Majority Leader Mitch McConnell can shield his GOP caucus from many difficult votes; not this one.
That means high anxiety for Republican senators facing re-election in 2020. Thom Tillis of North Carolina, Cory Gardner of Colorado and Martha McSally of Arizona, for example, must choose between the emergency's unpopularity and the wrath of Trump supporters, most of all the president himself.
Senate Republican strategists made some lobbying headway with a novel pitch to potential defectors. Stick with Trump on this one, while voting for a measure curbing presidential power on future emergencies.
Then Pelosi undercut the ploy, announcing the House wouldn't even consider it. A few hours later, Trump told Republicans he opposed it, too.