Ailing GOP Senator John McCain defended Mueller on Twitter, praising his "honesty and integrity" and saying it's "critical" the investigation continue "unimpeded".
The president is reportedly particularly annoyed that Mueller's team has issued subpoenas to the Trump Organization for documents related to deals it has done in Russia.
Republican Senator Jeff Flake, a frequent Trump critic, said it appeared the president's latest comments seemed to be preparing the ground for the firing of Mr Mueller.
Trump, the New York Times reported Sunday evening, is feeling unchained in recent days. "A lot of voters are getting tired of this act".
The firing came from a yet-to-be released report by the Inspector General of the FBI showed that McCabe lied to the FBI and leaked information to the press. "We can't in Congress accept that", said Flake.
This weekend, traders continued to focus on Washington and Trump's embattled presidency. "But the tweets confirm that he has corrupted the entire process that led to Mr. McCabe's termination and has rendered it illegitimate", he added.
He recounted, "A month ago I asked Chairman (Charles) Grassley (R-Iowa) to hold a hearing on the escalating politicized attacks on the Justice Department and the FBI".
Trump's major agenda push this week will highlight his plan to tackle the opioid crisis. Mueller is a Republican. But suspicions he was cast out for political reasons have been stoked by Trump's incessant public campaign for his ouster.
That should have been the headline.
Despite his low popularity among the general electorate, Trump's standing remains relatively strong among likely Republican primary voters here.
But some former campaign advisers have urged Mr Trump to be combative, warning him that that the investigation poses an existential threat to his presidency. There is a direct line from McCabe to Peter Strzok and Lisa Page and Bruce Ohr-all of whom were anti-Trump partisans and engaged in behavior that raises legitimate questions about their trustworthiness. Initially Mr Dowd said he was speaking for the president but later clarified he was "speaking for myself".
THE FACTS: He's incorrect to say "no crime" was found. "Because we're a rule of law nation", he said. Democrats on the other hand responded sharply, criticizing the justice department of being politicized. "They don't fall in love with anyone".
MSNBC debuted a spanking new segment with Axios on Monday, set to air just before Morning Joe daily, based on Allen's "1 Big Thing" - the scoop that leads his flagship newsletter Axios AM.
CNN wasted no time attacking Trump and his administration. Such moves further raise the entry barrier for potential challengers.
But the Mueller probe is more than prosecutorial overreach. Any dismissal would have to be carried out by Rod Rosenstein, the Trump-appointed deputy attorney general who has publicly expressed support for Mueller.
House Speaker Paul Ryan said through a spokeswoman that "Mr. Mueller and his team should be able to do their job".
Similarly, the Democratic primary challenge by then-Sen.
The President was also a registered Democrat from 2001 until 2009.
Sanders and Biden have stopped by the state during the past year.
Trump sent this out just as the Russia story hit a profound-and pro-Trump-moment. Lou D'Allesandro, a longtime Democratic power broker in New Hampshire.
Others also have an interest. "I have work to do".