The day of reckoning for American politics has arrived. Voters will decide the $5 billion debate between President Donald Trump's take-no-prisoner politics and the Democratic Party's super-charged campaign to end the GOP's monopoly in Washington and statehouses across the nation.

There are indications that an oft-discussed "blue wave" may help Democrats seize control of at least one chamber of Congress. But two years after an election that proved polls and prognosticators wrong, nothing is certain on the eve of the first nationwide elections of the Trump presidency.

"I don't think there's a Democrat in this country that doesn't have a little angst left over from 2016 deep down," said Stephanie Schriock, president of EMILY's List, which spent more than ever before — nearly $60 million in all — to support Democratic women this campaign season. "Everything matters and everything's at stake," Schriock said.

All 435 seats in the U.S. House are up for re-election. And 35 Senate seats are in play, as are almost 40 governorships and the balance of power in virtually every state legislature.

While he is not on the ballot, Trump himself has acknowledged that the 2018 midterms, above all, represent a referendum on his presidency.

Should Democrats win control of the House, as strategists in both parties suggest is likely, they could derail Trump's legislative agenda for the next two years. Perhaps more importantly, they would also win subpoena power to investigate the president's many personal and professional missteps.

The midterm elections will also test the strength of a Trump-era political realignment defined by evolving divisions among voters by race, gender and especially education.

Trump's Republican coalition is increasingly becoming older, whiter, more male and less likely to have a college degree. Democrats are relying more upon women, people of color, young people and college graduates.

The political realignment, if there is one, could re-shape U.S. politics for a generation. Just five years ago, the Republican National Committee reported that the GOP's very survival depended upon attracting more minorities and women. Those voters have increasingly fled Trump's Republican Party, turned off by his chaotic leadership style and xenophobic rhetoric. Blue-collar men, however, have embraced the unconventional president.

One of the RNC report's authors, Ari Fleischer, acknowledged that Republican leaders never envisioned expanding their ranks with white, working-class men. "What it means to be Republican is being rewritten as we speak," Fleischer said. "Donald Trump has the pen, and his handwriting isn't always very good."

A nationwide poll released Sunday by NBC News and The Wall Street Journal details the depth of the demographic shifts. Democrats led with likely African-American voters (84 percent to 8 percent), Latinos (57 percent to 29 percent), voters between the ages of 18-34 (57 percent to 34 percent), women (55 percent to 37 percent) and independents (35 percent to 23 percent). Among white college-educated women, Democrats enjoy a 28-point advantage: 61 percent to 33 percent.

On the other side, Republicans led with voters between the ages of 50 and 64 (52 percent to 43 percent), men (50 percent to 43 percent) and whites (50 percent to 44 percent). And among white men without college degrees, Republicans led 65 percent to 30 percent.

Democrats hope to elect a record number of women to Congress. They are also poised to make history with the number of LGBT candidates and Muslims up and down the ballot.

While Trump is prepared to claim victory if his party retains Senate control, at least one prominent ally fears that losing even one chamber of Congress could be disastrous "If they take back the House, he essentially will become a lame-duck president, and he won't win re-election," said Amy Kremer, a tea party activist who leads the group Women for Trump. "They'll do anything and everything they can to impeach him," she said. Indeed, powerful Democratic forces are already pushing for Trump's impeachment, even if Democratic leaders aren't ready to go that far.