Top Republican Senator Collins joins anti-Trump bandwagon

In a blow to Donald Trump, top Republican Senator Susan Collins has announced that she would not vote for him as he lacks the "temperament" and "judgement" required for the post, the latest party senator to renounce the presidential nominee.

"I will not be voting for Donald Trump for President," Collins, who represents the State of Maine in the US Senate, said in an op-ed in The Washington Post yesterday.

Trump, she argued, does not reflect historical Republican values nor the inclusive approach to governing that is critical to healing the divisions in the country.

Collins, the most senior senator to split publicly with the presidential nominee, said her conclusion about Trump's unsuitability for office is based on his "disregard" for the precept of treating others with respect, an idea that should transcend politics.

"Instead, he opts to mock the vulnerable and inflame prejudices by attacking ethnic and religious minorities. Three incidents in particular have led me to the inescapable conclusion that Trump lacks the temperament, self-discipline and judgement required to be President," she wrote.

Collins wrote, she is deeply concerned that Trump's lack of self-restraint and his barrage of ill-informed comments would make an already perilous world even more so.

"It is reckless for a presidential candidate to publicly raise doubts about honouring treaty commitments with our allies. Trump's tendency to lash out when challenged further escalates the possibility of disputes spinning dangerously out of control," she wrote.

Defending her decision not to support Trump, Senator Collins said some will say that as a Republican she has an obligation to support her party's nominee.

"I have thought long and hard about that, for being a Republican is part of what defines me as a person. I revere the history of my party, most particularly the value it has always placed on the worth and dignity of the individual, and I will continue to work across the country for Republican candidates," she said.

"It is because of Trump's inability and unwillingness to honour that legacy that I am unable to support his candidacy," Collins wrote.

She joined the few other Republican senators to repudiate the party's nominee for president.

Senators Lindsey Graham, Mark Kirk, Ben Sasse, Dean Heller and Jeff Flake have all said they would either not vote for Trump or adamantly voiced their resistance to the notion.

Senator Ted Cruz, who was defeated by Trump in the primary race, had urged conservatives to "vote your conscience" at the Republican national convention.