At the brief press conference, Tzintzún Ramirez said West is the clear choice when it comes to issues such as gun safety, women's rights and immigration.
She also said that his success would be a significant step forward in "bringing together Texans of diverse backgrounds" to represent Texas.
In the primary election on March 3, Hegar received 22% of the votes while West had 15%. Tzintzún Ramirez followed closely behind West with 13% of the vote before she conceded in the race.
West has represented the 23rd Senatorial District for Dallas County for more than 20 years since he was first elected in 1993. West is the managing partner of West & Associates LLP and has also served as the convention chair on the Texas Democratic Party.
West said at the March 9 press conference that his campaign will reach out to others in hopes of gathering more endorsements. This week, West said he expects former U.S. Rep. Chris Bell and Michael Cooper to endorse his campaign as well.
Tzintzún Ramirez's endorsement was West's "first significant endorsement," however, and West said he doesn't "take this lightly."
The runoff election will be held on Tuesday, May 26. Whoever wins the election will face Republican John Cornyn in the U.S. Senate general election in November.
You can learn more about Royce and Hegar's race here.
MORE ON TEXAS SENATE RACE:
- Here's what you missed at KVUE's U.S. Senate Democratic primary debate
- Highlights from KVUE's U.S. Senate Democratic primary debate
- KVUE hosts U.S. Senate Democratic primary debate
- MJ Hegar leads the Democratic U.S. Senate candidates, UT, TT Poll finds
- Meet the Texas Democrats running for US Senate
- Several Austin Democrats endorse State Sen. Royce West for U.S. Senate