Pete Buttigieg endorsed Joe Biden

Pete Buttigieg endorsed Joe Biden in Dallas Monday night, further narrowing the Democratic field's group of moderates in the former vice president's favor.

The state of play: The two spoke on the phone Sunday evening after the former South Bend mayor announced his departure from the race. With Amy Klobuchar also dropping out and planning to endorse Biden at Monday's rally in Dallas, the race is now down to four major candidates — Biden, Bernie Sanders, Elizabeth Warren and Mike Bloomberg.

Between the lines: The optics of Klobuchar and Buttigieg on the same stage — after the two candidates relentlessly attacked each other at debates — helps turn the moderates' unifying message into a real narrative.

• That being said, earning endorsements was never Biden's weakness. He's racked up more Democratic Party endorsements than any other candidate, including one from former Senate Majority Leader Harry Reid earlier on Monday.

The big picture: Biden's team also wants to use its own momentum via a post-South Carolina fundraising boost to score significant victories on Super Tuesday.

• The Biden team feels like "a clear choice" is emerging between him and Bernie Sanders, according to a campaign aide.
• His closing argument ahead of Super Tuesday will focus on the idea that voters don't desire a political revolution — a key refrain of the Sanders campaign — and instead want results.
• People close to Biden's team think he should keep pushing a message that "progressive" means progress, centering the campaign's argument ahead of Super Tuesday on the idea that Biden can get things done while Bernie can't.

The bottom line: This development isn't a total surprise, as Buttigieg's speech after dropping out sounded a lot like what Biden has been saying — and signaled a desire for the party to coalesce around a more moderate candidate.