Sen. Cory Booker announced Monday morning that he is dropping out of the presidential race, with three weeks to go before the Iowa caucus.

In a message to supporters, Booker cited fundraising struggles and his failure to make the debate stage, and said he no longer sees a path to victory.

“Our campaign has reached the point where we need more money to scale up and continue building a campaign that can win — money we don’t have, and money that is harder to raise because I won’t be on the next debate stage and because the urgent business of impeachment will rightly be keeping me in Washington,” Booker wrote.

Booker did not qualify for the December debate, and also failed to qualify for the debate in Iowa on Tuesday.

The New Jersey senator, and former mayor of Newark, has long been considered a rising star in Democratic politics. But he never broke out of the low single-digits in early state polling.

Booker’s campaign reported raising $6.6 million in the fourth quarter. That was his best fundraising quarter, but he still trailed well behind the frontrunners.

His exit from the race leaves the Democratic field lacking the diversity it had at the outset. Sen. Kamala Harris and Julian Castro, the former Housing and Urban Development secretary, also dropped out in recent weeks. Andrew Yang remains in the race, but he did not reach the polling threhold to qualify for Tuesday’s debate.

Only six candidates will appear at the debate, hosted by CNN and the Des Moines Register: Former Vice President Joe Biden, Sen. Bernie Sanders, Sen. Elizabeth Warren, former South Bend (Ind.) Mayor Pete Buttigieg, Sen. AMy Klobuchar and Tom Steyer.