Already, there's murmuring: What about a Walker-Rubio ticket? Or a Rubio-Walker one?

“I've actually had quite a few people -- grassroots supporters, donors and others -- who have made that suggestion,” Wisconsin Gov. Scott Walker (R) said in an interview with Bloomberg Politics on Thursday, when asked if he would be at all interested in partnering with Sen. Marco Rubio (R-Fla.).

Granted, it's early -- Walker has not even announced if he will run or not, saying that he wants to wait until after his state's two-year budget is completed in early July -- but speculative political matchmaking has already begun. And these two have a lot in common: They are both 40-somethings with kids who talk up their humble roots and rank as some of the least wealthy potential presidential contenders.

But there has been a little bit of sparring between the two. In late April, both were in the Des Moines area for a Saturday evening political forum at a mega-church. Earlier that day, Rubio said in a meeting with the Des Moines Register editorial board that there was "no way" a governor like Walker could handle foreign relations.

"Governors can certainly read about foreign policy, and take briefings and meet with experts, but there is no way they'll be ready on Day 1 to manage U.S. foreign policy," said Rubio, now 44, according to the Des Moines Register.

Walker, upon hearing about this comment, fired back: “I think he’s questioning how Ronald Reagan was ready.”

“Governors innately have the ability to lead," said Walker, 47, standing in a down-home restaurant called the Machine Shed. "We are required every day to use our cabinet to make decisions -- not just give speeches, not to just travel to foreign places, but to ultimately make decisions.”

And then there was this tweet, from Walker's son:

But then Walker sent out this tweet on Rubio's birthday:

"I like Marco Rubio a lot," Walker said in the interview with Bloomberg's Mark Halperin on Thursday. "Obviously, I'm deferential to governors. I think there's a lot we bring to the table as having proved executive experience. But I do like Marco Rubio. I think he and I have similar thoughts on national defense and foreign policy. Overall, I like him."

But, Halperin asked, would Walker be okay with a Rubio-Walker ticket instead of a Walker-Rubio one?

"Yeah, Marco and I joke about it," Walker said. "We'd just probably have to arm wrestle over who would be top of the ticket."