Emily Ward of the Washington Examiner probes Mitt Romney’s new role as U.S. senator.

Mitt Romney, the 2012 GOP nominee, is setting himself up as the Republican in the Senate who is most willing to criticize President Trump and block his agenda.

With the death of McCain, the 2008 GOP nominee, last year Romney has assumed the Arizonan’s mantle in the Senate of self-styled “conscience” of the Republican party, buoying Democrats on occasion and building an alternative power center in the party – and perhaps even positioning himself for a 2024 presidential bid, though by then he would be 77.

Last Tuesday, Romney was the only Senate Republican to vote against Trump judicial nominee Michael Truncale, citing Truncale’s disparaging comments about former President Barack Obama. Romney was one of four GOP senators in April poised to block the appointment of Trump pick Herman Cain to the Federal Reserve Board, until Cain dropped out.

Since arriving in the Senate in January – after a campaign in which he had been supportive of the president – Romney has turned himself into one of Trump’s most outspoken Republican critics, penning a New Year’s Day op-ed attacking Trump’s character and arguing that the president had “not risen to the mantle of the office.” Following the release of special counsel Robert Mueller’s report in April, Romney said he was “sickened” by Trump’s actions.

On Sunday, Romney was back at it, attacking the president’s character.”I think he could substantially improve his game when it comes to helping shape the character of the country,” Romney said on CNN.