He’s served in Congress for more than 25 years and in the Senate for more than nine, but through much of Sen. Bernie Sanders’ (I-Vt.) campaign for the presidency, not a single fellow senator had endorsed him.

That changed Wednesday when Sen. Jeff Merkley (D-Ore.) threw his backing behind his colleague from Vermont. 

Writing in the op-ed pages of the New York Times, the second-term senator said former secretary of state Hillary Clinton would be “a strong and capable president.”

“But Bernie Sanders is boldly and fiercely addressing the biggest challenges facing our country,” he wrote. 

Merkley described his own working-class upbringing in Oregon and argued that Sanders was best equipped to fight for families such as his own. He praised Sanders’ positions on trade, climate change, campaign finance and banking.

“It has been noted that Bernie has an uphill battle ahead of him to win the Democratic nomination,” he wrote. “But his leadership on these issues and his willingness to fearlessly stand up to the powers that be have galvanized a grass-roots movement. People know that we don’t just need better policies, we need a wholesale rethinking of how our economy and our politics work, and for whom they work.”

Merkley’s endorsement comes more than a month before his home state’s May 17 primary. But as he explained Wednesday morning on MSNBC’s “Morning Joe,” Oregon votes by mail — and ballots will be sent out in the next couple of weeks.