Trump is campaigning furiously in the battleground states of Ohio, North Carolina, and Florida, which he must win, yet the election may be decided by Utah, which has six votes.

Evan McMullin, a Mormon from Utah running as an independent , is close to  Trump according to the polls:

[I]n Utah, Evan McMullin, the Mormon independent candidate, is marginally second to Donald Trump and beating Hillary ... Donald Trump 32, Evan McMullin 29 and Hillary Clinton 28.

According to the New York Times report of August 9, 2016:

The first signs of Mr. Trump's troubles in Utah date to early March, when Mitt Romney, the 2012 Republican presidential nominee and a Mormon who is beloved in the state, gave a speech here warning that Americans were being duped by Mr. Trump.

Mitt Romney, the Republican nominee in 2012, a Mormon, is very popular in Utah.  He received 72.8% of the vote in 2012, and McCain received 62.5% in 2008.

There is no question that if Romney had endorsed and supported Trump, then Utah would be a safe state for him.  But the polls show a close race, and Trump had to have Pence campaign in Utah on October 26 instead of Ohio, Iowa, North Carolina, and Florida.

Romney chose not merely to remain silent about his preference, but to attack Trump.  In addition, Utah congressman Jason Chaffetz had un-endorsed Trump.

Romney has not formally endorsed McMullin, but McMullin sent out a fundraising appeal to Romney contributors based on a list of contributors supplied by Romney.

Interestingly, George Romney, Mitt's father, refused to support Goldwater, the 1964 Republican nominee.

If Mitt Romney does not want Hillary as president, then he should have not publicly attacked Trump.  He should have put the interest of our country above his personal views about Trump.  Trump's political agenda of repealing Obamacare, reducing taxes, border control, defeating ISIS, rebuilding the military, reducing regulations, and re-negotiating trade deals is closer to Romney's agenda in 2012 than Hillary's agenda.

In summary, Trump will probably win the battleground states everyone says he has to win, but he may lose the election because of Utah's six votes.