Democratic Sens. Dianne Feinstein and Barbara Boxer on Thursday endorsed Kamala Harris in the California Senate race, backing the state attorney general even though she’s running against a fellow Democrat, Rep. Loretta Sanchez.

The support from Feinstein and the retiring Boxer, whom Harris is trying to succeed in the Senate, is the latest sign of how much of the Democratic Party establishment has rallied behind Harris.

In July, President Barack Obama and Vice President Joseph R. Biden Jr. endorsed Harris, who is seeking to become just the second African-American woman to serve the Senate. 

Harris and Sanchez won the top two spots in the state’s open primary in June to advance to the general election, and Harris has been the prohibitive front-runner in the race even before the two senators’ support.

“I said at the start of the race between Attorney General Kamala Harris and Congresswoman Loretta Sanchez that they were both my friends and supporters. Therefore, I have stayed neutral,” Boxer said in a statement. “However, I also said that if differences developed that indicate that one candidate emerges as the progressive choice, that I would endorse the individual.

“That day has come,” she said.

[Poll: California Senate Race Tightens Slightly]

Sanchez has attempted to court Republican-leaning business organizations, without a candidate of their own in the race, to support her campaign.

The move has largely failed to pay off, however. Polls show Harris holding a comfortable advantage.

“In this U.S. Senate campaign, Kamala has been a consistent voice of unity and optimism at a time when too many political leaders have tried to divide our communities along racial and religious lines,” Feinstein said in a statement. “I wholeheartedly endorse Kamala’s campaign and look forward to having a strong partner in Kamala Harris serving alongside me in the U.S. Senate.”