A Republican senator’s denouncement of Donald Trump may have cost him his own reelection bid.

In his book, titled “Conscience of a Conservative”, Jeff Flake wrote that the “strategy is difficult to detect” in the “tweeting life of our president”.

“Influencing the news cycles seems to be the principal goal; achieving short-term tactical advantage, you bet. But ultimately, it's all noise and no signal,” he added.

The President has repeatedly proven he is not immune to criticism, and Politico reported last month that Mr Trump has spoken openly of spending $10m out of his own pocket to defeat Mr Flake in the 2018 midterms.

Mr Flake has frequently clashed with Mr Trump on issues such as immigration and international trade. The Arizona senator 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.

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Mr Flake was also critical of Mr Trump throughout the presidential campaign, especially following the release of “Access Hollywood” footage that showed the then-candidate bragging about sexual assault.

The Arizona senator noted in his book 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 said on cable channel MSNBC: “If we ascribe the worst motives to our opponents and demean them and call them clowns or losers, you just lose the ability to sit down and solve the big issues and actually enact conservative policy.