You remember the great Tea Party wave of 2010. That's when Sarah Palin, in a last grasp at political relevance, crisscrossed the United States in support of a new wave of populist Republicans vowing to take their country back and keep the government's hands off Medicare, a health program for seniors that just happened to be run by the government.
Voters never got the irony in that. Republicans gained 63 seats in the House of Representatives, taking control of the lower chamber in the biggest sweep in more than 60 years, and picked up six more seats in the Senate. No matter that the election of Class of 2010 led to the internecine warfare between mainstream and Tea Party Republicans that eventually cost House Speaker John Boehner his job. The GOP victory that November effectively ended Barack Obama's hopes of becoming a transformational president. His legislative agenda was dead. Gridlock ensued.
You can draw a straight line from that Tea Party election, which launched the populist challenge to the GOP establishment, and the rise of Donald Trump. But in a karmic demonstration of what-goes-around-comes-around in politics, the monster the Tea Party enabled now threatens to undo the fortunes of the Class of 2010. Mr. Trump, the Ripley's-worthy GOP nominee, risks being such a drag on down-ballot candidates that many of the Republicans swept in by the Tea Party wave could be swept out in an anti-Trump tsunami in November.
Of course, Democratic nominee Hillary Clinton's lead in the opinion polls, nationally and in key swing states, has shrunk quite a bit since her August postconvention bounce. Nagging voter doubts about one's honesty, reinforced by one's endless lack of forthrightness about one's e-mails, will do that to a candidate. Nagging doubts about Ms. Clinton's health, fed by her near-collapse Sunday, could drag her further down in the polls.
Still, Mr. Trump's unpopularity threatens to make one-term senators out of as many as half a dozen politicians who rode the 2010 Tea Party wave to Congress, more than enough to hand control of the upper chamber to the Democrats. Senators such as New Hampshire's Kelly Ayotte and Mark Kirk of Illinois were never card-carrying Tea Partiers, but would likely never have won their seats without the insurgent populist energy that drove Republicans to the polls in 2010. Mr. Kirk's victory was particularly sweet for the GOP, since he won Mr. Obama's former Senate seat.
This time, Mr. Kirk is cutting his ties to the pitchfork crowd as fast as he can. He insists he will not vote for his own party's nominee, whom he has called "too racist and bigoted for the Land of Lincoln." He has run TV ads reminding voters that he "bucked his party to say Donald Trump is not fit to be commander-in-chief." It's a strategy that carries its own risks in alienating Mr. Trump's core supporters. And it probably won't work, anyway. Mr. Kirk is likely to lose his seat.
Just as improbably, Ms. Ayotte is trying to have her cake and eat it, too. She says she will vote for Mr. Trump, but not endorse him, whatever that means. Though she is well-liked, Ms. Ayotte is fighting for her political life against the state's Democratic governor, Maggie Hassan, and a rush of anti-Trump sentiment. It will be a miracle if she survives.
The same anti-Trump mood threatens to doom Wisconsin's Ron Johnson and Pennsylvania's Pat Toomey, both ardent Tea Party supporters in 2010. An open Senate seat in Indiana that the GOP won in 2010 also looks set to return to the Democratic fold this year. So far, however, incumbent GOP Senators Marco Rubio and Rob Portman look strong in the swingiest states of them all, Florida and Ohio, respectively.
Still, most number crunchers predict the Democrats will retake the Senate, depriving the GOP of a united congressional front against a Clinton White House. The combination of districts gerrymandered to favour the GOP and the concentration of Democratic support in urban areas should limit GOP House losses to about 20 seats. It would likely take a wave election, with Ms. Clinton winning the presidency by more than six percentage points, to flip the House, too.
A Democratic hat trick – with the party winning the White House and both chambers in Congress – is still a possibility, however. It would mean the difference between a Clinton presidency that picks up where the Obama agenda stalled in 2010 and the unsatisfying (for Democrats) triangulation that characterized Bill Clinton's tangles with a GOP House. If only it weren't for those damn e-mails.