WASHINGTON ― Sen. Elizabeth Warren (D-Mass.) endorsed Graham Platner in the competitive Maine Democratic primary to decide who will take on Republican Sen. Susan Collins in November.

Warren’s endorsement is a significant boost for Platner, whose chief rival in the crowded Democratic primary, Gov. Janet Mills, has the full backing of party leadership. In a video statement posted by Platner’s campaign, Warren touted Platner’s blue-collar bona fides and military background.

“Graham actually knows hard work,” Warren says in the video. “He’s an oyster farmer in Maine. Graham knows the consequences of Donald Trump sending our service members to fight endless wars in the Middle East. He’s a combat veteran who was deployed in Iraq and Afghanistan.”

The winner of the June primary will face Collins in November, one of several Senate contests that could tip control of the chamber back into Democrats’ hands.

Warren’s endorsement comes at a critical time for Platner. The Mills campaign hit Platner with an ad this week highlighting gross Reddit posts he wrote in 2013. “How about people just take some responsibility for themselves and not get so f**ked up they wind up having sex with someone they don’t mean to?” Platner wrote in one since-deleted post, part of a cache that came to light last fall, prompting Platner to apologize.