When the dust clears from next Tuesday's bitterly fought midterm elections, one of two starkly different scenarios will likely emerge.

The more probable one would see resurgent Democrats regaining control of the U.S. House of Representatives, enabling them to put a brake on President Donald Trump by ending two years of dormant congressional oversight and launching scrutiny into his administration's policy shifts and allegations of corruption.

Still, it remains possible, though increasingly unlikely, that Trump and the Republicans will yet avoid the normal midterm rejection of the party in power, setting the stage for further efforts to cut taxes and renew the GOP effort to scrap the remaining parts of Obamacare.

In any event, Republicans seem virtually certain to avert full-scale disaster by retaining – or even increasing – their majority in the U.S. Senate, the principal goal of Trump's frenetic final week campaigning. That would enable the GOP to continue its successes of the last two years of installing conservative federal judges, including filling any further possible vacancies on the Supreme Court.

Significant changes won't be confined to Washington. Besides regaining the House, Democrats are poised to recapture power in many major state governorships and legislatures, laying the basis for moderating the GOP's post-2010 success in drawing favorable legislative and congressional district lines.

Meanwhile, the usual pre-election uncertainties have been increased by the dramatic and horrifying events of the last week: the brutal massacre of 11 worshipers in a Pittsburgh synagogue by an avowed anti-Semite; the murder of two black people at a Kentucky grocery store; and the dispatch by a Florida Trump backer of potentially fatal pipe bombs to an array of top Democrats and Trump critics.

The searing headlines stemming from these events temporarily foiled Trump's effort to refocus the election on one of his favorite issues, the specter of illegal immigration and especially the alleged threat from a "caravan" of several thousand Central Americans, still many hundreds of miles from the Texas border. He responded by dispatching 5,200 troops and, somewhat inadvertently, disclosed he plans to issue an executive order denying birthright citizenship to the children of illegals, a move that is almost certainly illegal but possibly potent politically.

In any case, most analysts still expect the first scenario to prevail because of normal midterm trends and indications there will be an outpouring of Democrats, especially women, determined to avenge their party's 2016 defeat. Another factor: Trump's dogged refusal to broaden the political base that provided his narrow victory two years ago.

Democratic recapture of the House would signal a partial retreat from the Trump tsunami that gave the GOP complete control of the federal government in 2016. But this year's changes won't likely be as sweeping and will probably foretell little about the prospects for Trump's re-election two years hence.

In the last month, Trump and his allies succeeded in ratcheting up previously lagging Republican enthusiasm by assailing the way Democrats sought to block the Supreme Court nomination of Brett Kavanaugh and stirring fears of an imminent invasion of illegal immigrants by exaggerating the threat from the group of several thousand fleeing northward from Central America.

Trump's efforts may help to foil some Democratic Senate hopefuls and incumbents in the "red" states he carried in 2016 and enable the GOP to add a seat or two to its narrow 51-49 majority.

At the same time, he has avoided the mainly suburban battlegrounds where he is unpopular and where most competitive House seats are located. Democrats need to gain 23 House seats for control, and many of their likely victories are in areas Hillary Clinton carried against Trump two years ago.

With more than two dozen GOP-held House seats still rated as tossups, the most respected handicappers have analyzed the likely results by projecting a range of Democratic gains. For example, David Wasserman of the Cook Political Report estimates Democrats will gain 25-40 seats, just above the level needed to regain a majority.

With these results considered the most likely for some weeks, both parties have reportedly been preparing for a transformed Washington landscape, Democrats by mapping potential Trump administration targets for oversight and the White House preparing to go on defense.

One unanswered question is whether – and how quickly – House Democrats might launch an impeachment inquiry against Trump. Despite calls for action from activists, party leaders say they will wait to see if special counsel Robert Mueller concludes that Trump obstructed justice in his opposition to the probe or colluded with the Russians to win the presidency.

It seems like the 2018 campaign has been going on forever. And when the dust finally clears next week, the focus will quickly shift to a 2020 presidential race that is already well under way.

– Carl P. Leubsdorf is the former Washington bureau chief of the Dallas Morning News. Readers may write to him via email at carl.p.leubsdorf@gmail.com.