Rubio takes to Twitter to defend his decision to back Trump at the Republican convention after earlier calling him a 'con man' – and dismisses 'keyboard cowboy' who questions his turnaround

Marco Rubio is defending his decision to cast aside dire warnings he made during the primaries about the threat he said Donald Trump posed to the republic now that he says he'll attend the GOP convention in Cleveland – would even consider speaking on behalf of Trump.

'I want to be helpful. I don't want to be harmful, because I don't want Hillary Clinton to be president,' Rubio told CNN's Jake Tapper on Thursday.

It is common for politicians to have to walk back past statements made in the heat of a primary campaign, but Rubio has more ground to cover than most, having labeled Trump 'wholly unprepared to be president of the United States,' and having gone after him as an 'erratic individual' with 'no ideas of any substance on the important issues.'

In the interview, Rubio declined to revisit his many differences with Trump by saying he spent nearly a year discussing them already, saying, 'I think they're well understood.'

Rubio said he'd help the Republican nominee win the White House. 'I don't want Hillary Clinton to be president. If there's something I can do to help that from happening, and it's helpful to the cause, I'd most certainly be honored to be considered for that,' he said. 

Rubio took to Twitter to push back against a column in the Washington Examiner that said Rubio 'doesn't have the courage to stand up for his stated convictions.'
 

'Far from being an inspirational moral leader, Rubio has shown himself to be more of an opportunistic politician with his finger to the wind,' wrote Philip Klein in the article, headlined 'Donald Trump has exposed Marco Rubio.'

Rubio tweeted Friday that it a 'funny piece,' then said it was 'easy to be a "keyboard cowboy."' 

Keyboard cowboy: Rubio pushed back on an article that called him an 'opportunistic politician'

Despite his turnaround, the one role Rubio said he won't take on is that of running mate. Rubio self-accessed that he 'wouldn't be the right choice' for Trump's ticket.

'He won the nomination and he deserves to have a running mate that more fully embraces some of the things he stands for,' Rubio told CNN.

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ON BOARD: Marco Rubio says he'll attend the Republican nominating convention and would even be willing to speak on Donald Trump's behalf from the stage

BACKHANDED COMPLIMENT: Trump later said on Twitter, 'Poll data shows that @MarcoRubio does by far the best in holding onto his Senate seat in Florida. Important to keep the MAJORITY. Run Marco!'

Two months after his White House dreams were dashed, Rubio has come around to the idea of a Trump presidency.

'I'm gonna go to the convention. I don't know if I'll have a role in the convention, but I have a lot of people going there that were supporters,' he told Tapper in an interview that will air in full on Sunday morning. 

Asked if he'd give a speech if asked, Rubio said, 'Yeah. I want to be helpful.'

Rubio said he'd release his 167 delegates to Trump now that he's officially the GOP nominee and holding on to them would be 'irrelevant.' 

He reiterated his position on Friday in a tweet that said, 'If you can live with a Clinton presidency for 4 years thats your right. I cant and will do what I can to prevent it.'

Playing defense: Rubio took to Twitter to defend his decision to back Trump, after calling him a 'con man' during the campaign

Taking liberties: Rubio says there are only two 'legitimate' candidates on the ballot, though libertarian Gary Johnson says he'll be on the ballot in 50 states

After the clip aired Trump gave him a backhanded compliment on Twitter, tweeting, 'Poll data shows that @MarcoRubio does by far the best in holding onto his Senate seat in Florida. Important to keep the MAJORITY. Run Marco!'

Rubio is facing increasing pressure to stay put in the Senate. 

CNN reports that Republicans, worried about their tenuous majority in the U.S. Senate, are asking the Florida senator to reconsider his retirement.

The 45-year-old politician isn't budging, and the filing deadline for the race less than a month away.

'It's unlikely,' Rubio told Capitol Hill reporters on Thursday. 'I haven't had time to talk to about it, but my sense of it is nothing has changed,' the senator added. 

He told Tapper it's a 'safe assumption' he'll run for office again one day in some capacity.

'I can tell you I enjoy public service. If there's an opportunity to serve again in a way that I feel passionate about, I'll most certainly think I would explore it,' he said, according to CNN. 'But I don't know where I'm going to be in two years. I don't know what my life will look like then.'

Rubio dropped out of the presidential race on March 15, after losing his home state primary to Donald Trump. He planned not to run for Senate again

The No. 2 Senate Republican John Cornyn publicly joined the chorus calling on Rubio to run on Thursday.

'It's obviously a very personal decision, but I think it be good for the party, it would be good for the Senate – I'd like to see him do it,' Cornyn told CNN. 'I hear a lot of buzz around here from members and others; that's a conversation we need to have.' 

Behind closed doors on Capitol Hill, CNN said that Senate Majority Leader Mitch McConnell surveyed a room full of Senate Republicans to see who wanted Rubio – who was not in attendance – to enter the race. 

Nearly everyone raised their hands, while the top Republican encouraged Rubio's colleagues to exert a little peer pressure on the former presidential hopeful. 

Later, the news network spotted Sen Roger Wicker cornering Rubio on the Senate floor. 

'It is a very real development,' Wicker said, saying Rubio running again in Florida was 'certainly within the realm of possibility.'  

Rubio dropped out of the presidential race on March 15, the night of the Florida primary, after being crushed in his home state primary by the now-presumptive GOP nominee, Donald Trump. 

Long before bowing out, Rubio said he would not be running for re-election. 

He used that as an excuse when political rivals hammered him for missing votes, as he often opted to be out on the campaign trail instead of Washington, D.C.

It was also widely reported that he was just not that into his job, with some associates even saying that he 'hated' it.

'I don't know that "hate: is the right word,' he was qouted as saying in an October report in the Washington Post. 'I'm frustrated.'

But now, even as Rubio's popularity at home took a hit because of his presidential run, he's still a known name and can bring in donations. 

Other Florida Republicans in the race do not have his incumbent advantage in the purple state either in a year that could see Democratic turnout go up.

Hopefuls on the Republican side include Lieutenant Gov. Carlos Lopez-Cantera, a close friend of Rubio's, whose interest in the race might color the sitting senator's decision, Reps. David Jolly and Ron DeSantis  and two men from the private sector, Carlos Beruff and Todd Wilcox.  

The Democrats, meanwhile, have Reps. Patrick Murphy and Alan Grayson in the running. 

Rubio told Florida reporters Thursday, 'We need to make sure we get behind the right candidate in the primary to win. As I said, I think Carlos Lopez-Cantera is a very good candidate.

'I understand the argument and the people who are coming forward and asking me to reconsider are people I respect and enjoy serving with. But I have a really good friend running for the Senate who I think is a good candidate, who I think gives us a real good chance to win if he were to be nominated,' he said, according to Politico.