Democratic Congressman Brad Schneider has endorsed State Sen. Daniel Biss for governor — marking the first major congressional endorsement in a crowded gubernatorial primary that’s still nine months away.

It’s another earmark of the unprecedented Democratic primary race to try to unseat Republican Gov. Bruce Rauner — which has seen major unions offer their endorsements and millions poured into campaign funds much earlier than usual.

Schneider is throwing his support behind Biss — one of seven other Democratic candidates — in a swing district that saw wins last year by Democrats U.S Sen. Tammy Duckworth and Illinois Comptroller Susana Mendoza. Rauner won the district by 12 points in 2014.

10th District Rep. Brad Schneider has endorsed Daniel Biss for governor. | Rich Hein/Sun-Times

Last year saw the third election in a row that Schneider and Republican Bob Dold, considered moderate candidates, had faced off against each other to represent the far north suburban district.

Schneider’s district encompasses parts of Cook and Lake counties, including Fox Lake, Grayslake, Highland Park, Lake Bluff, Lake Forest, Waukegan and Zion, among other suburbs. It traditionally has a high voter turnout.

Biss, D-Evanston, kicked off his campaign on March 20, while taking shots at both Rauner and Illinois House Speaker Michael Madigan. He has about $1.68 million in his campaign fund.

In a statement, Schneider said Biss has the qualities “desperately” needed in the next governor.

“He is honest about our problems, unafraid to challenge conventional wisdom with new ideas, and keenly focused on what the people of Illinois need,” Schneider said. He noted Biss’ lead on issues like income inequality, women’s health care and protecting the environment.

Biss called Schneider “a thoughtful and valued partner at the federal level, consistently demonstrating what strong advocacy on behalf of his constituents looks like.”

Biss also gave the congressman credit for “defending Illinois residents against Donald Trump’s attacks.”

Another gubernatorial candidate, State Rep. Scott Drury, D-Highwood, is also in Schneider’s district, and the two have hosted events together. Drury didn’t endorse a candidate in Schneider’s 2016 primary race against Highland Park Mayor Nancy Rotering.

Reached for comment, Drury noted he didn’t ask for Schneider’s support.

“We appreciate the work Brad does in Congress. Consistent with past practice, we did not seek his endorsement in this race,” Drury said in a statement. “This remains a two-way race — those with proven loyalties to the Madigan machine versus our campaign. We like our odds.”

Democratic challengers also include J.B. Pritzker, Chris Kennedy, Ald. Ameya Pawar, Bob Daiber, Tio Hardiman and Alex Paterakis.