Democratic presidential candidate Elizabeth Warren is throwing her support behind Cook County State’s Attorney Kim Foxx, endorsing the incumbent in her heated race for reelection.

“When Cook County first elected Kim Foxx to the State’s Attorney office, it not only gained a seasoned advocate but a champion invested in rethinking the county’s approach to criminal justice reform,” the senator from Massachusetts said in a statement. “Kim is an effective public servant who leads with compassion, and I’m confident that when reelected, Kim Foxx will continue to bring those qualities to the office.”

Warren’s endorsement comes less than a week before the Iowa caucuses, the crucial first-in-the-nation winnowing of the presidential field. Warren was in fourth place in Iowa in a New York Times/Siena College poll released Saturday, the same day the Des Moines Register endorsed her in the race.

Vermont Sen. Bernie Sanders led the Democratic field with 25% of likely caucus-goers in that poll. South Bend, Ind., Mayor Pete Buttigieg had 18%, former Vice President Joe Biden had 17%, and Warren had 15%.

Warren lost ground from earlier polls, but given the latest survey’s error margin of plus-or-minus 4.8 percentage points, Sanders’ lead could be thin, with Buttigieg, Biden and Warren statistically tied for second.

Warren’s endorsement is the highest profile backing yet for Foxx. The first-term prosecutor has also drawn support from Gov. J.B. Pritzker, Mayor Lori Lightfoot, Cook County Board President Toni Preckwinkle, and Illinois Senators Dick Durbin and Tammy Duckworth.

In a statement, Foxx said she’s “honored” to get Warren’s endorsement.

“We know our working communities stand to lose the most when exposed to a broken criminal justice system,” Foxx’s statement continued. “Our reform on bond, conviction integrity and cannabis have undoubtedly helped bring more equitable justice to these communities. Having Sen. Warren’s endorsement is a testament to the work we’ve only just started on here in Cook County.”

Three Democratic challengers stand in the way of Foxx and a second term. Those challengers in the March primary are former prosecutor Bill Conway, former 2nd Ward Ald. Bob Fioretti and ex-prosecutor Donna More.

Last month, the progressive veterans organization VoteVets endorsed Conway, who serves as a U.S. Naval Reservist intelligence officer.

Former prosecutor Christopher Pfannkuche and retired Cook County Circuit Court Judge Pat O’Brien are also in the race, running on the Republican ballot. Pfannkuche received the endorsement of the city’s Fraternal Order of Police.

Warren is the latest nationally known name to back Foxx. Last week, Grammy-winning singer-songwriter John Legend and Color Of Change PAC, the political action committee of the nation’s largest online racial justice group, endorsed Foxx.