While many of his loyal supporters believed that the move was unacceptable, Senator Ted Cruz (R) finally endorsed Republican presidential contender Donald Trump.

Cruz was Trump's fiercest rival for the Republican nomination. He even refused to encourage his supporters to back the business magnate after he lost the nomination during the Republican National Convention in July.

"After many months of careful consideration, of prayer and searching my own conscience, I have decided that on Election Day, I will vote for the Republican nominee, Donald Trump," said the Texas Senator in his Facebook page.

Being loyal to his party, Cruz said he has moral obligation to support any Republication nominee.

While admitting his differences with Trump, the senator said seeing Democratic presidential candidate Hillary Clinton winning the presidency is unacceptable.

"[E]ven though I have had areas of significant disagreement with our nominee, by any measure Hillary Clinton is wholly unacceptable - that's why I have always been #NeverHillary," he said.

He also reiterated the reasons that prompted him to rally support to Trump. Among these are the appointment of justices at the Supreme Court, his objection to the Obamacare, the U.S. energy programs, immigration policies, national securities and internet freedom.

"If Clinton wins, we know - with 100% certainty - that she would deliver on her left-wing promises, with devastating results for our country. My conscience tells me I must do whatever I can to stop that," he pointed out.

He also doubted the fitness of Clinton for the presidency while highlighting that her policies would harm millions of Americans.

Cruz was the last man standing between Trump and the nomination. During the Republication primary, Trump launched series of personal attacks against Cruz including that of his wife and father.

Cruz, on the other hand, dubbed Trump a "pathological liar" and "amoral."