Kirk says he plans to announce his Senate candidacy on Monday

U.S. Rep. Mark Kirk is pulling the trigger.

The Highland Park Republican is set to announce his "candidacy for statewide office" at 10:30 a.m. Monday in his North suburban 10th District, a Kirk spokesman said Wednesday.

A Republican source has told the Daily Herald the five-term congressman has been drumming up support for a pending Senate bid. The GOP has been in disarray lately over whether Kirk would run or not, with the Illinois Republican Party chairman recently throwing his hat in the ring as well.

Chairman Andy McKenna has said he will not run if Kirk does.

Kirk has also debated a run for governor, but talk lately has been of the Senate bid. Kirk has also told the Daily Herald he was less interested in running the state than being a U.S. senator.

Kirk has faced criticism from his party for voting for President Barack Obama's cap-and-trade legislation. But party brass, especially at the national level, largely still see him as the GOP's best shot at winning back the seat once held by Peter Fitzgerald of Inverness and Obama.

Sen. Roland Burris, a Chicago Democrat appointed to the seat by ousted Gov. Rod Blagojevich, has announced he will not run for election. Potential Democratic contenders include Illinois Treasurer Alexi Giannoulias, Chicago Urban League CEO Cheryle Jackson and Merchandise Mart boss Chris Kennedy.

Petitions to get on the ballot are set to be circulated next month. The primary is set for February.