Chicago Mayor Rahm Emanuel has signed a petition urging lawmakers to make Illinois the 10th state to legalize gay marriage.

On Wednesday, Lambda Legal announced Emanuel had joined their effort.

“Mayor Emanuel has been on the forefront in advocating for the freedom to marry for same-sex couples in Illinois, we're very pleased that he's taken the step of signing the pledge to show his support for our efforts to bring marriage to Illinois,” Jim Bennett, regional director for the Midwest Regional Office of Lambda Legal, said in a statement.

Sponsors of the bill in the House and Senate said they wouldn't press for a vote until they had a majority. A push earlier this month during the Senate's quick lame-duck session was suddenly called off. The bill's champion in the chamber, Senator Heather Steans, said she called off the vote because three supporters were not present.

Supporters are now looking for passage in the spring session of the General Assembly, which officially begins on February 5.

Emanuel promised in November to become “very involved” in the issue.

“I will continue to advocate, as I have since a congressman, that we also pass marriage equality and end the discrimination on the books,” Emanuel told reporters.

(Related: Illinois Governor Pat Quinn on gay marriage bill: We must succeed.)