The theme of the day is “United Together,” and the scheduled speakers are meant to bring in the wing of the party who would have preferred that Vermont Sen. Bernie Sanders be the one to take on Donald Trump this fall.

The most prominent speaker will be Sanders himself. The self-described democratic socialist endorsed Clinton earlier this month after refusing to do so for longer than some expected. Though Sanders has hinted at expanding his campaign into a broader progressive coalition after the general election, the Vermont senator has made it clear that, for now, his goal is to defeat Trump, whom he considers unfit for the presidency.

Also speaking on Monday will be First Lady Michelle Obama and Massachusetts Sen. Elizabeth Warren.

Warren is giving the final speech of the night. While Sanders may have a certain authority with progressives, it is Warren who more likely represents the future of the coalition. She has been Clinton’s most effective attack dog thus far, hitting Trump viciously and forcing the Republican nominee to respond to her rather than focusing on the actual Democratic ticket.

While she’ll likely attack Trump plenty on Monday, Warren will also have to focus some of her energy on telling fans of hers why they should vote for Clinton, a politician many of her supporters consider insufficiently progressive. Warren has been the Democratic Party’s loudest and most consistent voice in favor of tougher Wall Street regulation. Given that one of the biggest criticisms of Clinton among progressives is her perceived closeness to the financial sector, a full throated endorsement from Warren could go a long way to assuaging voters’ concerns on the matter.