Sen. Elizabeth Warren, D-Mass., plans to campaign for Iowa Senate candidate Zach Wahls this month, adding firepower to a raging battle between progressive outsider candidates and the Democratic Party establishment.

Wahls, a state senator, is pitted against state Rep. Josh Turek, whom many perceive as the favorite of Democratic leaders in Washington, in the June 2 primary. The winner will take on Republican Rep. Ashley Hinson in what promises to be a closely watched race in the fight for control of the Senate.

"Zach Wahls is running to shake things up," Warren said in a statement announcing her May 10 visit to a Wahls rally in Des Moines. "He's taking on a corrupt system that's rigged against working families; a system where giant corporations, their lobbyists, and their super PACs funnel millions to candidates like Ashley Hinson, so those politicians let them jack up prices on groceries, prescriptions drugs, and the basics Iowans need to get by."

Warren, who had already endorsed Wahls, announced her trip to the state Friday morning, one day after an establishment favorite, Gov. Janet Mills, dropped out of a heated Maine Democratic Senate primary. Mills' decision to suspend her campaign all but ensures that Graham Platner, an oyster farmer and veteran backed by Warren, Sen. Bernie Sanders, I-Vt., and other progressives, will win the right to face five-term Republican Sen. Susan Collins in November.

The two races are among several House and Senate contests across the country that have become proxies in the war for control of the Democratic Party's future. With the party out of power in the White House and Congress, the influence of past presidents Joe Biden, Barack Obama and Bill Clinton diminished and a free-for-all expected in the 2028 Democratic presidential primaries, the stakes in each race — and all of them collectively — are sky-high for both entrenched establishment figures and the outsiders who seek to seize power from them.

Polling in Iowa has been sparse. A poll by Vote Vets Action Fund, a group that supports Turek, found him up by 20 points in April. A Teamsters local released an earlier survey concluding that the union-backed Wahls was leading by 18 points.

In a statement, Wahls welcomed the news that Warren, who campaigned for president in Iowa in 2020 and finished fourth in the Democratic caucuses, is returning to lend her voice to his campaign.

"She has spent her career standing up to the corporate special interests that have rigged our economy, and that's exactly the fight Iowans want their next senator to take on," he said.

The seat is open because Republican Sen. Joni Ernst decided not to seek a third term. A Democrat has not won a Senate seat in Iowa since Tom Harkin captured a fifth term in 2008.