Democrats scrambled on Monday to assess the damage after Hillary Clinton's loss, marking the start of a season of jockeying within the party over who will be its next leader.

On a conference call with supporters late Monday, President Barack Obama congratulated Clinton on a "history-making" race, but he called on his party to assess what went wrong and retool at a grass-roots level.

"We have better ideas, but they have to be heard for us to actually translate those ideas into votes and ultimately into action," Obama said.

Meanwhile, Hillary Clinton addressed congressional lawmakers on a separate conference call, acknowledging the impact of her loss.

"No one is sorrier than me," Clinton said, according to a Democrat on the call. "Heartbreaks don't heal overnight, and this one won't."

Clinton noted that the election is one that should be studied, and she urged lawmakers to fight for the party's values harder than ever. She said she is "grateful" that "in the end our vision for America earned more votes."

Yet, Democrats this week are beginning to strategize about how to regroup in the new Trump era, which has left them locked out of the White House and out of power in the Senate and the House of Representatives.

Calls for new leadership and ideas have prompted several Democrats to put their names forward to lead the party.

On Monday, the country's first Muslim lawmaker and a prominent liberal voice in the House, Rep. Keith Ellison, D-Minn., announced that he would run for chairman of the Democratic National Committee.

In a show of strength, Ellison rolled out 40 endorsements, including Senate Minority Leader Harry M. Reid (Nev.) and Reid's expected successor, Sen. Charles E. Schumer, D-N.Y.

Also endorsing Ellison on Monday were Sen. Amy Klobuchar, D-Minn., Sen. Chris Murphy, D-Conn., Rep. Raúl M. Grijalva, D-Ariz., and Rep. G.K. Butterfield, D-N.C.

"Democrats win when we harness the power of everyday people and fight for the issues they care about," Ellison said in a statement. "It is not enough for Democrats to ask for voters' support every two years. We must be with them through every lost paycheck, every tuition hike, and every time they are the victim of a hate crime. When voters know what Democrats stand for, we can improve the lives of all Americans."

Ellison was one of the first and few sitting lawmakers who endorsed Sen. Bernie Sanders, I-Vt., over Hillary Clinton in the Democratic primary. And he was also one of the Democrats who recognized early on that Trump posed a potentially formidable challenge in this election.

Trump showed unexpected strength in industrial Midwestern states, where he lost by fewer than two percentage points to Clinton. That represented a sea change and a narrow miss for Democrats, especially when compared with Mitt Romney's nearly eight-point loss to Obama in the 2012 presidential election.

"We must champion the challenges of working families and give voters a reason to show up at the polls in 2018 and beyond," Ellison said.

In a news conference on Monday, Obama also acknowledged that Clinton's loss marked the erosion of Democratic support in parts of the country that he had won, in part because her campaign believed that the path to victory would not go through predominantly white and working-class corners of the electoral map that helped win Trump the White House.

Obama named Iowa as a state he won not "because the demographics dictated" it but because he spent time campaigning in small towns and counties where he was the underdog.

"There's some counties maybe I won, that people didn't expect, because people had a chance to see you and listen to you and get a sense of who you stood for and who you were fighting for," Obama said.

Several other Democrats have put their names forward to lead the party, including former Maryland Gov. Martin O'Malley, South Carolina Democratic Party Chairman Jaime Harrison and the DNC's national finance chairman, Henry R. Muñoz III and former DNC chair and Vermont Gov. Howard Dean.

On Monday morning during an appearance on MSNBC's "Morning Joe," Dean emphasized that the job is one that should require a full-time commitment, a long-standing criticism of the last full-time DNC chair, Rep. Debbie Wasserman Schultz, D-Fla., who served in the position while also holding a congressional seat.

"You cannot do this job if it's not full-time. Period," Dean said.