Donald Trump aide steps up bid to block possible Mitt Romney's nomination

Romney vigorously challenged Trump's fitness for presidency, including his foreign policy credentials

A top Donald Trump adviser has warned that the president-elect's supporters would feel "betrayed" if he tapped former Massachusetts Governor Mitt Romney as secretary of state, a move that would put a once fierce Trump critic in a powerful Cabinet post.

The comments from Kellyanne Conway deepened a highly unusual push by some Trump allies to stop the president-elect from nominating Romney.

The extraordinary public nature of the effort has also stirred speculation that it could be a Trump-approved attempt to humiliate a prominent Republican who staunchly opposed him throughout the presidential campaign.

Conway, who served as Trump's campaign manager and is part of his transition team, said her opposition to Romney reflected what she's been hearing from Trump voters.

"People feel betrayed to think that Gov Romney, who went out of his way to question the character and the intellect and the integrity of Donald Trump, now our president-elect, would be given the most significant cabinet post of all," Conway said in one of several television interviews on Sunday. She said Romney was "nothing but awful" to Trump for a year.

Conway's opposition to Romney is also said to be supported by Steve Bannon, the controversial conservative media executive who will serve as Trump's White House senior adviser.

People involved in the transition process said Trump's decision on his secretary of state did not appear to be imminent.

Trump is an avid consumer of television news and his advisers and allies often use their appearances to send messages to Trump or the Republican establishment. Still, it's rare for Conway and other close aides who speak frequently with Trump in private to be so explicit about their views in public.

That makes it seem at least possible that Conway was acting at Trump's behest by suggesting the president-elect was being generous by considering his former political rival.

Romney, the 2012 GOP nominee, vigorously challenged Trump's fitness for the presidency, including his foreign policy credentials. In a wide-ranging condemnation of Trump in March, Romney said the businessman's bombast was "alarming the allies and fueling the enmity of our enemies." 

Trump responded by mocking Romney, calling him a "choker" and saying he "walks like a penguin".