WASHINGTON (AP) — Senate Majority Leader Mitch McConnell urged fellow Republicans on Wednesday to abandon their effort to overrule President-elect Joe Biden's election triumph, directly rebuking defeated President Donald Trump and asserting that the GOP drive threatened the country's democratic foundations.

“The voters, the courts and the states have all spoken,” said McConnell, R-Ky., as the Senate debated a challenge by a handful of GOP lawmakers to the 11 electoral votes that Arizona cast for Biden. “They've all spoken. If we overrule them, it would damage our republic forever.”

Arizona's were the first of several states’ electoral votes that some Republicans are challenging, encouraged by Trump’s groundless charges that the election was riddled with fraud. Congress seemed certain to reject all those challenges and formally affirm Biden’s victory. All 50 states have certified the electoral votes.

The showdown came on one of the most convulsive days in the country's recent political history.

The Senate suspended its deliberations after chanting protesters gained entry to the Capitol, prompting police to lock down the building. Some lawmakers tweeted that they were sheltering in place. Thousands of pro-Trump protesters rallied in the nation's capital, answering appeals by Trump himself, who addressed supporters gathered outside the White House.

In addition, with party control of the chamber at stake in a pair of runoff elections in Georgia, Democrats won one of the races and seemed on the brink of winning the other. Two Democratic victories would produce a 50-50 Senate, which Democrats would control with the tie-breaking vote of Vice President-elect Kamala Harris.

In recent weeks, McConnell has challenged Trump, whose term ends Jan. 20, with increasing frequency, including helping override Trump's veto of a defense bill and working to kill Trump's push for $2,000 economic stimulus payments to Americans.

But McConnell minced no words Wednesday as he spoke on the Senate floor against Trump's futile bid to reverse his reelection loss.

“If this election were overturned by mere allegations from the losing side, our democracy would enter a death spiral," McConnell said. “We would never see the whole nations accept an election again. Every four years would be a scramble for power at any cost."

After four years in which Trump has frequently resorted to falsehoods, McConnell said, “We cannot keep drifting apart into two separate tribes with a separate set of facts and separate realities." He said the country risked taking “a poisonous path where only the winner of an election actually accept the results."

Despite McConnell's opposition, 13 GOP senators had said they would join scores of their House colleagues Wednesday and object when Congress formally affirms Biden’s Electoral College victory.

Even before Wednesday, McConnell warned his colleagues that the showdown was risky because it will force GOP senators, including those in potentially tough 2022 reelections, to decide whether to support or oppose the tweet-happy Trump in a fight they were sure to lose. In mid-December, McConnell privately warned them that pressing the issue would force a “terrible vote,” even as he publicly congratulated the Democrat Biden for his win, ignoring Trump's refusal to concede.

McConnell has actively avoided confrontation with Trump whenever possible, but he is plainly fed up with the Trump chaos.

But McConnell was powerless to prevent the objections, which are allowed by the Constitution and federal law if one representative and one senator challenge a state's electoral votes. He also faced overpowering political dynamics, including some senators' expected 2024 presidential ambitions, others' desire to protect themselves from 2022 primaries prompted by an offended Trump, and the temptation to use the fight to raise money and buttress support from Trump's ardent followers.

Trump’s claims of voter fraud have been rejected by Republican and Democratic officials in state after state and numerous judges, including the conservative-dominated Supreme Court. Trump’s former attorney general, William Barr, has said there is no evidence of fraud that could change the election outcome.

Freshman Sen. Josh Hawley, R-Mo., has said he will challenge Pennsylvania's electoral votes. Sen. Ted Cruz, R-Texas, is leading a group of 11 senators who want to create a commission to examine groundless allegations of election fraud. Both men are expected to run for president in 2024.

Sen. Kelly Loeffler, R-Ga., may challenge the results in her state. Pennsylvania, Arizona and Georgia were all pivotal states that Biden carried on his way to his 306-232 Electoral College win.

McConnell's most powerful allies are with him, with GOP Whip John Thune of South Dakota earning a Twitter threat from Trump after predicting the Senate effort would “go down like a shot dog.”

McConnell is trying to steer his colleagues to a conservative argument that Congress shouldn't overrule states' election decisions. He's gained momentum in recent days, winning support from influential members including moderate Sen. Rob Portman, R-Ohio, and conservative Sens. Tom Cotton, R-Ark., and Pat Toomey, R-Pa.

Aides expect a majority of GOP senators to join McConnell and all Democrats in shooting down the electoral vote challenges. Cotton is considered another presidential contender.

McConnell, 78, has been the Republican leader since 2007 and is the longest-serving Senate GOP leader in history. But his status as majority leader is in peril for reasons outside the intraparty Electoral College tussle.

McConnell hasn’t shied from past battles with the party’s conservative base. He’s won more than not lately, but in 2010 and 2012 fringe GOP candidates in Nevada, Colorado and Indiana appeared to cost the party seats. But he turned the tide in 2014, beating back a primary challenge of his own and leading the GOP to Senate control after eight years in the minority.

Cruz's group includes all four freshmen Senate Republicans, a troubling sign for McConnell as stalwart allies such as Sens. Lamar Alexander, R-Tenn., and Pat Roberts, R-Kan., have retired. Each first-term senator pledged fealty to Trump in their campaigns and are casting the first vote of their Senate careers in line with Trump’s wishes.