Facing federal scrutiny in a broadening public corruption probe, state Sen. Martin Sandoval submitted his letter of resignation to the Illinois Secretary of the Senate on Wednesday, effective New Year’s Day.

Writing “with heavy heart,” Sandoval’s announcement came about two months after FBI agents raided the powerful Southwest Side Democrat’s offices.

Sandoval has not been charged with any wrongdoing.

“Since 2003, it has been an honor of a lifetime to serve the State of Illinois and fight on behalf of the good people of the Southwest Side of Chicago/Suburban West Cook,” Sandoval wrote.

“Respect for my constituents and the Senate has convinced me that this action is necessary in order to proceed without distraction to the important work that needs to be accomplished for working families throughout the state of Illinois in the future.”

He wrote his resignation from his legislative seat under letterhead as chairman of the influential Senate Transportation Committee, though Sandoval resigned from that post in October. That resignation came just before authorities released the search warrants outlining what federal agents went looking for Sept. 24 at Sandoval’s Chicago home and government offices in Springfield and Cicero.

Before submitting his latest resignation on the eve of the long Thanksgiving weekend, Sandoval had not made any public appearances since the raids. He was a no-show for the fall veto session in Springfield earlier this month.

With the feds breathing down his neck, Sandoval had faced numerous calls to step down. Gov. J.B. Pritzker had sought his ouster as chairman of the Transportation Committee, concerned that the federal investigation could taint the state’s $45 billion capital infrastructure program — a signature piece of legislation for the Democratic governor that Sandoval helped spearhead in the spring session.

Pritzker’s office did not immediately respond to a request for comment Wednesday.

Sandoval, 55, was a Water Reclamation District commissioner before he was first elected to the state Senate in 2003.

Unredacted warrants show the feds zeroed in on Sandoval’s ties to the clouted red-light camera company SafeSpeed, a video gambling magnate and numerous lobbyists and political organizations in a probe that has put several suburbs under the microscope. McCook Mayor and Cook County Commissioner Jeff Tobolski is also being scrutinized by the feds. Around the same time as the Sandoval raids, agents sought records from other towns in his Senate district, including Lyons and Summit.

How that ties into a web of other activity by federal investigators spanning the ranks of the Illinois political power structure over the past few months is unclear.

State Rep. Luis Arroyo stepped down earlier this month after being charged with bribing a state senator — identified by the Chicago Sun-Times as Vernon Hills Democrat Terry Link — while state Sen. Tom Cullerton, D-Villa Park, faces embezzlement charges involving the Teamsters.

And Ald. Ed Burke (14th) is facing a racketeering indictment for allegedly shaking down a Burger King franchisee for legal business.

Sandoval’s daughter works for ComEd, which has also been subpoenaed for records on its lobbying activities.

Once Sandoval’s resignation is official at a minute past noon on Jan. 1, Democratic committeepeople for the 11th Senate District will have 30 days to name someone to fill Sandoval’s seat. That person will serve until the results of next year’s November general election are finalized in early December of 2020.

Next week, the state Board of Elections will open a special filing period, from Tuesday through the following Monday, for candidates who want to run in the March primary to serve out Sandoval’s current term. Candidates need 1,000 to 3,000 signatures to get on the primary ballot.