House Majority Leader Steny Hoyer (D-Md.) picked up endorsements from five more senior Democrats on Tuesday in his battle against Rep. James Clyburn (D-S.C.) for the position of minority whip.

A total of seven Democratic committee leaders, including four who had not previously declared their support for Hoyer, wrote a letter backing the Maryland lawmaker. They included Reps. Barney Frank (Mass.), Henry Waxman (Calif.), Nick Rahall (W.Va.) and Howard Berman (Calif.).

“Steny Hoyer is a tested leader who can help Democrats rise to the challenge of the next Congress, protect the interests of the middle class, and win back the majority,” the lawmakers wrote.

Rep. John Tierney (Mass.), a seven-term congressman, also committed his support to Hoyer on Tuesday, a source close to the majority leader told The Hill.

The endorsements extend Hoyer’s wide lead in public backers of his bid. He now has more than 50 supporters, although he will need close to 100 Democrats to clinch a victory in the secret ballot vote. Hoyer’s strategy appears to be rolling out public endorsements in an effort to force Clyburn to negotiate for a lower-ranking leadership post.