Trump critic Jeff Flake rebukes president as he says he will not seek re-election: 'I will not be complicit or silent'

White House Press Secretary Sarah Huckabee Sanders says 'it’s probably a good move'

In an extraordinary day of Republican infighting, Republican Senator Jeff Flake announced that he will not seek re-election as a protest against President Donald Trump's behaviour.

Mr Flake - himself a frequent target of the President's personal jibes – delivered a strong rebuke to his own party for letting Mr Trump get away with “reckless, outrageous and undignified behaviour”.

The announcement came after Mr Trump spent much of the day trading insults with senior Republican Senator Bob Corker, mostly via Twitter. Mr Corker has previously said that he too will not run again in 2018.

In a passionate speech on the Senate floor, Mr Flake announced: “I rise today to say: Enough. We must dedicate ourselves to making sure that the anomalous never becomes normal.”

“We must never regard as 'normal' the regular and casual undermining of our democratic norms and ideals,” he added. “We must never meekly accept the daily sundering of our country - the personal attacks, the threats against principles, freedoms, and institutions, the flagrant disregard for truth or decency, the reckless provocations, most often for the pettiest and most personal reasons, reasons having nothing whatsoever to do with the fortunes of the people that we have all been elected to serve.”

With Senate Majority Leader Mitch McConnell and several other party colleagues in attendance, the Arizona senator said he has “children and grandchildren to answer to”, and so “I will not be complicit or silent” over the actions of Mr Trump.

“We must stop pretending that the conduct of some in our executive branch are normal. They are not normal,” Mr Flake declared. “When the next generation asks us, why didn’t you do something? Why didn’t you speak up? What are we going to say?”

Earlier, Mr Corker lambasted the President's tendency to disregard facts, saying Mr Trump has “great difficulty with the truth.”

Mr Trump responded to Mr Corker's comments on Twitter, writing: “Sen Corker is the incompetent head of the Foreign Relations Committee, & look how poorly the US has done.”

During a news conference, Mr McConnell refused to weigh in on the spat and shrugged off questions about their ongoing quarrel by saying Republicans are unified behind passing tax reform.

But Mr Flake's decision to retire rather than seek re-election puts him on what appears to be a growing list of senators who have nothing to lose by opposing Mr Trump. This will make it harder for the President to wield any influence to get his legislative priorities passed in the 100-member Senate, where Republicans have a narrow 52-seat majority.

After Mr Flake finished his speech, which garnered a standing ovation from some of his colleagues, Mr McConnell and fellow Arizona Senator John McCain lauded the Mr Flake as “a very fine man” and a “man of integrity, honour and decency”, respectively. Mr McCain, who himself has increasingly voiced his misgivings about several of Mr Trump's policies and objectives, also hugged Mr Flake.

Mr McCain, diagnosed with brain cancer earlier this year, just this past week questioned “half-baked, spurious nationalism” in America’s current foreign policy.

Mr Flake first made his plans to retire known to the Arizona Republic, telling the newspaper: “There may not be a place for a Republican like me in the current Republican climate or the current Republican Party.”

The junior senator has long been critical of Mr Trump and has frequently clashed with the President on issues such as immigration and international trade.

Mr Flake is among the Senate's Republican advocates for comprehensive immigration reform, and he is a faithful defender of the North American Free Trade Agreement, which the President has threatened to withdraw from unless Canada and Mexico agree to significant alterations of the accord. Mr Flake also denounced Mr Trump throughout the presidential campaign.

The Arizona legislator noted in his book released earlier this year how Mr Trump at a summer 2016 meeting predicted that their differences would cost Mr Flake his seat in the Senate.

“You've been very critical of me,” Mr Trump told Mr Flake, according to the senator.

Mr Flake was already going to have a tough fight to re-win his seat in next year's election. Polls showed him to be unpopular in Arizona.

During a White House briefing, Press Secretary Sarah Huckabee Sanders told reporters that she hadn’t spoken to Mr Trump about the senator's decision.

“But I think that, based on previous statements and certainly based on the lack of support that he has from the people of Arizona, it’s probably a good move,” she said.