Two front-running 2020 Democratic presidential candidates, former Vice President Joe Biden and Vermont Senator Bernie Sanders, are sharply disagreeing about the U.S. assassination of Iranian commander Qassem Soleimani. Sanders has condemned the assassination and has introduced legislation, along with California Congressmember Ro Khanna, that would block funding for any military action “in or against Iran” without congressional authorization. Biden, meanwhile, has tried to use the increasing tensions to argue that his past foreign policy experience would make him the best president in the event the United States goes to war with Iran.

In more election news, former Democratic presidential candidate Julián Castro says he is endorsing Massachusetts Senator Elizabeth Warren for president.

Júlian Castro: “There’s one candidate I see who’s unafraid to fight like hell to make sure America’s promise will be there for everyone, who will make sure that no matter where you live in America or where your family came from in the world, you have a path to opportunity, too. That’s why I’m proud to endorse Elizabeth Warren for president.”

That’s Julián Castro speaking in a video he posted on Twitter Monday, just days after he dropped out of the race. Warren responded by tweeting, “You’ve been a powerful voice for bold, progressive change and I’m honored to have your support. Together, we’ll fight to make sure every single family in America has a path to opportunity.” Castro and Warren are hosting a campaign rally tonight in Brooklyn.