Scott Walker withdrawing his candidacy for the 2016 election back in September. | Getty Marco Rubio asked Scott Walker to endorse him

Marco Rubio, looking to capitalize on a wave of momentum, is pushing to win the support of a former rival: Scott Walker.

After last week’s debate in Boulder, Colorado, Rubio tried to initiate a phone call with the Wisconsin governor, who dropped out of the race for the Republican nomination in September. A source close to Walker, who requested anonymity to discuss the outreach, said the two connected by phone late last week.


That conversation, which lasted 15 to 20 minutes, began with friendly banter. The Florida senator asked Walker what he’d been up to since he departed the primary. Toward the end of the conversation, the source said, Rubio made a “hard ask” for Walker’s support.

Walker, though, is not planning on making an immediate endorsement of anyone in the GOP field. During the conversation, the Wisconsin governor told Rubio that he had not made a decision on who he will back and that he would not announce his support for a candidate until after the start of 2016.

While Walker has been courted by a number of Republican candidates since his exit, those close to the Wisconsin governor say Rubio is the first to formally ask him for his endorsement.

In recent weeks, Rubio also has made an aggressive push to win over Walker’s financial supporters. Last month, Rubio invited about 20 of the governor’s top bundlers for a private meeting at the offices of Weil Gotshal & Manges, a white-shoe law firm in New York City. Rubio has received the backing of a number of Walker donors, including Jonathan Burkan, Eric Anton and Julian Gingold.

Rubio has also sought the support of the Ricketts family, which own the Chicago Cubs and gave more than $5 million to a super PAC supporting Walker before he dropped out of the race.

Walker is scheduled to appear at an education event in Wisconsin with Jeb Bush on Monday, and he is planning to attend Tuesday's GOP debate.

Spokespersons for Walker and Rubio declined multiple requests for comment.