Des Moines, Iowa (CNN) Less than four weeks from the Iowa caucuses, former Vice President Joe Biden in many ways appears to be in a stronger position now than he was when he entered the 2020 presidential race .

Biden has defied perceptions that he is a weak front-runner, retaining his strength with non-white voters and ranking consistently as the candidate likely voters believe has the best chance to defeat President Donald Trump. Predictions that his age, penchant for gaffes and lengthy record would be his undoing have not come true.

Now, a confluence of events in the lead-up to the first primary votes being cast are playing to Biden's strengths.

National headlines have been dominated by the turmoil in Iraq and Iran , amplifying Biden's core message that he has the most experience on the world stage to be president.

"There is a smart way to counter them, to counter Iran -- and a self-defeating way. Trump's approach in my view is demonstrably the latter," Biden said in a foreign policy speech Tuesday in New York.

And with electability remaining at the forefront of Democratic voters' minds, Biden is racking up endorsements , including several from swing-district congressional Democrats this week.

Meanwhile, the Democratic foes who were most eager to attack Biden have either dropped out of the race or failed to qualify for the debate stage, leaving Biden to spar with Vermont Sen. Bernie Sanders in the sorts of predictable progressive-vs.-moderate spats that are well within the comfort zones of both candidates.

Biden's resilience in the Democratic race for president has again made him a target for his top competitors, setting up the potential for a heated match up at next week's debate in Iowa hosted by CNN and The Des Moines Register.

Increasingly, Biden's rivals are attempting to change voters' minds about his electability.

On CNN on Monday night, Sanders jabbed Biden for voting for the North American Free Trade Agreement and for voting to authorize the use of military force in Iraq under former President George W. Bush.

"You think that's going to play well in Michigan or Wisconsin or Pennsylvania?" Sanders said. "If we're going to beat Trump, we need turnout. And to get turnout, you need energy and excitement. And I don't think that that kind of record is going to bring forth the energy we need to defeat Trump."

And on Tuesday, Massachusetts Sen. Elizabeth Warren set up a new fight with Biden when released a plan to roll back several of the provisions of the 2005 bankruptcy law that she and then-senator fought over.

Biden's ultimate priority in the first half of February, in the Iowa caucuses and New Hampshire primary, is survival. Those two states' Democratic electorates have more white, college-educated voters -- one of Biden's poorer-performing demographics -- than many that follow.

Biden would like to win, but his campaign has been lowering expectations of a victory in the two states for months. What he needs is to advance to more diverse states in the Democratic race -- Nevada, then South Carolina, then California, Texas, southern states and more on Super Tuesday in early March -- with most of his existing support intact.

Polling in Iowa has been scant in recent weeks, but a CBS News poll released over the weekend showed Biden in a three-way tie with Sanders and former South Bend, Indiana, Mayor Pete Buttigieg. The same poll showed Biden and Sanders leading the pack in New Hampshire.

In Iowa, Biden is pressing his two biggest advantages over his Democratic rivals: His deep support from black voters, and the sense likely voters have consistently expressed to pollsters that Biden is the party's most electable candidate against Trump.

Over the next week, Biden's campaign is sending a host of diverse surrogates to Iowa.

The group includes Atlanta Mayor Keisha Lance Bottoms, California Reps. Ami Bera and Lou Correa, and Missouri Rep. Emanuel Cleaver.

The not-so-subtle message to Iowa's largely white electorate: Do you really want to vote for candidates like Buttigieg, who have made next to no inroads with non-white voters?

In recent days, Biden has racked up endorsements from swing-district members of Congress -- freshman Democrats who won in Republican-held seats in 2018. Virginia Rep. Elaine Luria, Pennsylvania Rep. Chrissy Houlahan and Pennsylvania Rep. Conor Lamb backed him Sunday.

Days earlier, Iowa Rep. Abby Finkenauer endorsed Biden, becoming the first member of the state's congressional delegation to endorse in the 2020 race. She then spent the weekend traveling the state with him, introducing him at events and urging attendees to caucus for the former vice president.

During his recent four-day swing through Iowa, at events, voters said Biden's electability was a driving force behind their support for him.

Chase Lampe, a 30-year-old high school government teacher in Des Moines, spoke with Biden on the ropeline after a Saturday night event in Des Moines. Biden leaned in and grabbed both of his shoulders after Lampe thanked Biden for being first -- ahead of former President Barack Obama -- to announce his support for same-sex marriage.

Lampe started the 2020 campaign season expecting to back former Texas Rep. Beto O'Rourke, then supported California Sen. Kamala Harris, and finally was interested in Buttigieg -- but said he's landed on Biden.

"The closer and closer we get to it, the more and more I want to win," he said.

Lampe said he was thinking not just about facing Trump, but down-ticket state races.

"It's important that the presidential candidate can do well here in Iowa because there's a chance we could win the Senate here in Iowa," he said.

Biden's campaign has argued that, while other candidates saw spikes in support (in the case of Harris, who has dropped out) or rose and then appeared to stall (like Warren), Biden has been at or near his floor for a long time -- and that Biden would climb as voters began to see the stakes rising.

"I don't know if there's any of the campaign that has a coalition as diverse and broad as ours," said Ras Smith, an Iowa state representative and the Biden campaign's Iowa director of coalition-building.

"I'm the youngest member of the Iowa Democratic caucus in the House. Rep. Finkenauer used to own that title. And I think the fact that he has the support of Rep. Finkenauer and myself speaks to kind of where we're at, what we're seeing, and there's movement in the state," Smith said. "People are starting to say, you know what? I think I've gotta go Joe."

Voters still have concerns about Biden. The worry expressed most frequently among early-state voters is his age (Biden turned 77 in November).

Deb Hansen, a retired dental hygienist in Johnston, said Saturday night she's considering Biden, Booker and Minnesota Sen. Amy Klobuchar. She said Biden "does a great job" and "connects well with the crowd," but she's worried about his age.

"If I knew who his vice president was -- if he puts Amy or Kamala in for vice president -- it's hands down," she said.

At the same time, national news developments have strengthened Biden's position: The crisis in the Middle East has moved foreign policy -- where Biden has long argued his decades of experience are an advantage -- to the forefront of the 2020 race. And Trump's impeachment, over efforts to get Ukraine to investigate Biden's son's business dealings there, gave Biden a big boost in online fundraising -- jumping 121% during impeachment proceedings compared to the weeks prior, his campaign said.

The morning after Trump ordered a strike that killed a senior Iranian commander in Iraq, Peggy Kaune, a retired nurse in Dubuque, said she's considering Biden and Sanders -- but that "it makes me nervous" that Sanders could be too liberal for the general election on foreign policy.

"I watched the news until three in the morning last night," she said. "It's just frightening. We've got to stop (Trump). He's got to be stopped."

And -- echoing the Biden campaign's argument that the former vice president's support has remained strong through attacks from Trump and his Democratic rivals largely because voters feel like they know him -- she said Biden is the candidate she trusts the most to meet the moment.

Biden, she said, has "got the experience, and his energy is really good. He gives me a lot of confidence."