Three Democratic candidates hoping to succeed Gov. Janet Mills said Friday that they will rank each other on the June 9 primary ballot, the latest example of candidates in the crowded gubernatorial field forming an alliance that excludes certain contenders.

Former Maine House Speaker Hannah Pingree, former Maine Senate President Troy Jackson and Secretary of State Shenna Bellows said they will list each other at the top of their ranked-choice ballots. All three trail former Maine Center for Disease Control and Prevention Director Nirav Shah in the limited polling that’s been done of the race.

Their campaigns said they will hold a news conference next week, and that they invited U.S. Senate candidate Graham Platner to join them at that Tuesday event. The campaigns did not say in what order they plan to rank each other.

Friday’s update is not too surprising. Bellows, Jackson and Pingree gathered along the Kennebec River in Hallowell last month at an event in which the Sierra Club of Maine said it is endorsing each of them. But it is another example in the governor’s race of candidates looking to team up against rivals.

In a statement, Shah’s campaign did not address the alliance.

“With two weeks to go, we’ll continue to be focused on earning the support of Mainers,” campaign manager Kayla vanWieringen said. “We look forward to being on the trail every day talking to voters about the issues they care about and the future of our great state.”

Earlier this month, Republicans Ben Midgley and David Jones told their supporters to rank the other candidate second in their seven-person primary. And GOP candidate Robert Wessels, a former Paris select board member, told his supporters to rank healthcare executive Jonathan Bush second. Bobby Charles has led the polls in the Republican race while alienating his opponents.

Friday’s news release from the campaigns of Bellows, Pingree and Jackson included warm words and compliments from each of the candidates toward one another. Bellows also took a dig at Shah without naming him by alluding to ads in support of him from an outside group that counts a pro-school voucher group as one of its funders. Bellows said she, Jackson and Pingree agree that “voucher schemes that drain funding from our public schools have no place in Maine.”

Platner, who is the presumed Democratic nominee in the effort to unseat U.S. Sen. Susan Collins, R-Maine, said Thursday that he is ranking Jackson first on his gubernatorial primary ballot, Bellows second and Pingree third.

Also on the Democratic gubernatorial primary ballot is green energy entrepreneur Angus King III, who was second behind Shah in a recent poll.