Scott Detrow

Former Vice President Joe Biden is defending his record on Social Security, amid increased criticism from the campaign of Vermont Sen. Bernie Sanders, which has repeatedly pointed to Biden's willingness as a U.S. senator to back spending freezes for Social Security and other entitlement programs.

The candidates' back-and-forth culminated — as most disputes in modern presidential campaigns do — in dueling Twitter posts Tuesday night.

How confident are Iowa Democrats in their choices, now two weeks out from the caucuses?

The response Renee Kleinpeter gave NPR when asked which candidates she has narrowed her choice down to could sum it up: four seconds of laughter.

"I'll go with anybody who could beat [President] Trump," she said after laughing. "I wish somebody could tell me."

Updated at 5:11 p.m. ET

Leading Democratic presidential candidates on Tuesday blasted President Trump's decision to kill Iranian Maj. Gen. Qassem Soleimani, casting it as a dangerous escalation in a volatile region.

Former Vice President Joe Biden delivered a speech in New York City in which he labeled the deadly strike as the latest in a series of "dangerously incompetent" steps taken by Trump.

Just days after ending his campaign for president, former Housing and Urban Development Secretary Julián Castro is endorsing Massachusetts Sen. Elizabeth Warren.

The two will hold a rally together Tuesday evening in Brooklyn.

Updated at 2:06 p.m. ET

A three-month window that began with a heart attack ended as Vermont Sen. Bernie Sanders' strongest fundraising quarter yet.

Sanders' campaign announced it raised $34.5 million in October, November and December — nearly $10 million more than he had raised in the previous quarter. According to the campaign, $18 million came in from 900,000 individual donations in December alone, as Sanders drew larger and larger crowds to rallies in early voting states such as Iowa and New Hampshire.

Updated at 10:05 a.m. ET

The former law professor in the 2020 field is the only presidential candidate to earn an A in a new scorecard, released on Wednesday by the grassroots progressive group Indivisible.

Updated at 3:25 p.m. ET

California Sen. Kamala Harris is dropping out of the presidential race, citing a lack of funds. She informed her campaign staff of the decision on a conference call and later sent an email to supporters, in which she wrote "my campaign for president simply doesn't have the financial resources we need to continue."

Former Massachusetts Gov. Deval Patrick is making a last-minute entry into the crowded Democratic presidential primary.

A source with direct knowledge of his decision tells NPR that Patrick has been making calls to Massachusetts and national elected officials and supporters to brief them on his plans and that he plans to formally enter the race as soon as Wednesday night.

Patrick's decision is about as last minute as it gets for a candidate who still wants to compete in the key early primary states: New Hampshire's filing deadline is Friday.

Updated at 7:35 p.m. ET

Former New York Mayor Michael Bloomberg is weighing a late entrance into the Democratic presidential primary, reversing course from this spring, when he said publicly that he would not run.

Massachusetts Sen. Elizabeth Warren has been calling for President Trump's impeachment since the spring. California Sen. Kamala Harris wasn't too far behind her. New Jersey Sen. Cory Booker's been pushing for it for months.

In fact, all six U.S. senators still running for president are backing the House's impeachment inquiry.

But now that the lawmakers may be getting what they want, many political operatives see it as a train wreck for their presidential campaigns.

Former Vice President Joe Biden appears to be ramping up his attacks on President Trump. Notably, he's also ramping up his defense of his own dealings in Ukraine.

Updated at 3:43 p.m. ET

Former Vice President Joe Biden called for President Trump's impeachment unless the White House complies with congressional requests for information about a call the president made to a Ukrainian leader.

"We have a president who believes there is no limit to his power," Biden said. "We have a president who believes he can do anything and get away with it. We have a president who believes he is above the law."

Updated at 1:50 p.m. ET

Friends, family, reporters and politicians gathered Saturday in downtown Washington, D.C., to remember journalist Cokie Roberts.

She was hailed as a "servant" of God and referred to as a "special singular soul" by those who delivered remarks.

Roberts died Tuesday at age 75 of complications from breast cancer. She had covered and commented on politics for NPR since 1978 and spent decades working for ABC News as well, including several years co-hosting the Sunday morning political show This Week.

Updated at 1:40 p.m. ET

Security concerns have prompted the Democratic National Committee to recommend nixing a plan that would have allowed Iowans and Nevadans to remotely caucus for candidates next year.

Supporters have long argued that "virtual caucuses" would open up Iowa's first-in-the-nation presidential contest, which requires caucusers to physically attend sometimes hours-long events to declare their choice for president.

Former Vice President Joe Biden plays up his Pennsylvania roots as much as anything and has heavily courted organized labor in his presidential campaign, but a key union in Biden's backyard is feeling neglected by the leading Democratic candidate.