Sen. Marco Rubio charged Sunday that President Obama has lost his political touch, accusing the incumbent of employing a "divisive" and "cynical" style that now pits Americans against one another -- tough words that come amid speculation the Republican senator is trying out for the No. 2 slot on the GOP presidential ticket. 

Rubio, without explicitly discussing his vice presidential aspirations, staunchly defended Republican candidate Mitt Romney over a series of recent controversies. And he launched broadside after broadside at Romney's presumed opponent. In an interview on "Fox News Sunday," he said President Obama has been in Washington so long -- he's been there seven-and-a-half years -- that he's starting to sound "just like anybody else in Washington." 

"All the things that made him different and special four years ago are gone," Rubio said. "And now all he does is run, dividing Americans against each other, obviously because he can't run on his record." 

Rubio rapidly has emerged as one of Romney's top defenders and top attack dogs. His comments on "Fox News Sunday" come one day after Obama held a pair of rallies officially kicking off his 2012 re-election campaign. 

Rubio, though, is just one of several Republicans thought to be on the short list -- a list which could include, among others, Virginia Gov. Bob McDonnell, Wisconsin Rep. Paul Ryan and New Jersey Gov. Chris Christie. Sen. Kelly Ayotte, a Republican New Hampshire senator, also recently stirred speculation about VP possibilities when she campaigned alongside Romney. 

Facing a competitive field, Rubio and Ayotte defended their credentials in Sunday show interviews. 

Ayotte, speaking on NBC's "Meet the Press," said "it's an honor to be mentioned in that vein." 

While saying she's focused on her state, she also said, "I have great experience as attorney general in the state," and further claimed to have "better experience" than Obama when he ran for the White House. 

Rubio made a similar pitch. Asked what makes him qualified for vice president, Rubio said he's not going to discuss that process but went on to describe his qualifications for U.S. Senate. Rubio touted his experience serving at the local government level and later moving up the ranks in the Florida state legislature to eventually serve as House speaker. 

"I'm certainly not the most experienced person in Washington, D.C. But by the same token, I certainly have experience in serving in government and particularly in the legislative branch in one of the largest states and more complex states in the country in terms of public policy," he said. He added that Obama has spent so much time in the capital that he's become "divisive, cynical ... always looking for the opportunity to pit Americans against each other in some sort of political calculation." 

Rubio, meanwhile, criticized Obama's economic record, accusing the president of pushing policies that make employers "afraid to hire." And he forcefully stood by Romney in his criticism last week of the Obama administration's handling of the escaped Chinese dissident who sought shelter in the U.S. Embassy. 

Chen Guangcheng left the embassy Wednesday to seek medical treatment and visit his family at a hospital. The move touched off several days of diplomatic confusion -- as Chen soon claimed he wanted to leave China out of fear for his family's safety despite initial U.S. claims that he wanted to stay in China and had received assurances from the Chinese government. 

After some diplomatic wrangling, Chen appears to now have the option to study abroad, in the United States. 

Romney, though, described the situation as a "dark day for freedom" and "day of shame" for the Obama administration as conflicting stories emerged earlier in the week. 

Asked whether Romney jumped the gun, Rubio said he did not -- and went on to suggest that the administration's handling speaks to a broader problem.   

"There's this propensity that this administration seems to have of an unwillingness to forcefully assert America's values," Rubio said. 

In a separate interview on ABC's "This Week," Obama campaign adviser David Axelrod accused Romney of "trying to score political points" with his criticism. 

As for the Democrats' vice presidential nominee, Vice President Biden said in an interview broadcast Sunday that he's it. 

"There is no question about it," Biden said, when asked on "Meet the Press" whether he's a "lock" for the position on Obama's ticket. 

"There's no way out. I mean, they've already printed Obama/Biden. You are looking at the vice presidential candidate of the United States of America."