Updated 3:18 p.m. | Rep. Jesse L. Jackson Jr. submitted his letter of resignation from the House on Wednesday, a spokesman for Speaker John A. Boehner, R-Ohio, confirmed.

In the letter to Boehner, the Illinois Democrat said that his resignation would be effective as of Wednesday, citing ongoing health issues.

“The constituents of the Second District deserve a full-time legislator in Washington, something I cannot be for the foreseeable future. My health issues and treatment regimen have become incompatible with service in the House of Representatives,” Jackson wrote.

Jackson  also acknowledged the ongoing federal probe into his conduct, without getting into details of legal matters.

“During this journey I have made my share of mistakes,” he wrote. “I am aware of the ongoing federal investigation into my activities and I am doing my best to address the situation responsibly, cooperate with investigators, and accept responsibility for my mistakes, for they are my mistakes and mine alone.”

Jackson’s resignation will be accepted and become official when the House gavels back into session next week. The move will set off a scramble to fill the safe Democratic seat in the Chicagoland area. Democratic Gov. Pat Quinn would have five days from the effective date of the resignation to announce the timing of the special election.

There will be no shortage of Democrats interested in running for the seat.

Jackson’s resignation comes amid news of the lawmaker’s plea negotiations with federal prosecutors about alleged misuse of campaign funds. The Illinois Democrat has been largely absent from the public eye and from Capitol Hill since June, when he began treatment for bipolar disorder, including a stint at the Mayo Clinic in Minnesota.

Several Chicago media outlets reported late Tuesday that Jackson had planned a staff conference call for Wednesday morning, but that was canceled.

Multiple reports say Jackson is under investigation by federal prosecutors in Washington over improper use of campaign money for personal use. It’s been rumored that any plea agreement would require Jackson to resign from Congress.

That probe is unrelated to a House Ethics Committee review of Jackson over the attempts by former Illinois Gov. Rod Blagojevich to sell the Senate seat vacated when Barack Obama became president. Blagojevich is serving 14 years in federal prison following conviction on a slew of corruption charges.

Minority Leader Nancy Pelosi, D-Calif., released a statement saying that she spoke with Jackson and his father, Rev. Jesse Jackson, Sr., on Wednesday afternoon.

“As he works to address his health, our thoughts and prayers are with him, his wife Sandi, his children as well as his parents,” Pelosi said. “We are grateful to him and his family for their longstanding record of public service to our country.”