WASHINGTON (AP): The Latest on the 2016 presidential race, which includes a Republican debate on Thursday night in Detroit (all times EST):

11:42 a.m.
Mitt Romney says Donald Trump lacks the temperament and the integrity to be president and that the GOP should pick one of the other three candidates.

He says, the only serious policy proposals that deal with the broad range of national challenges we confront today, come from Ted Cruz, Marco Rubio, and John Kasich. One of these men should be our nominee.”

He tells a University of Utah audience that “dishonesty is Donald Trump’s hallmark.”

The 2012 GOP presidential nominee says Trump imagined that he saw Muslims celebrating the September 11, 2001 attacks in New Jersey.

He adds: “His imagination must not be married to real power.”

11:36 a.m.
Mitt Romney says GOP front runner Donald Trump is dangerous – and a fake.

He tells an audience at the University of Utah Thursday morning that if Republicans choose Trump to be their presidential nominee, “the prospects for a safe and prosperous future are greatly diminished.”

The 2012 GOP presidential nominee says the billionaire developer is not what he seems, saying, “A business genius he is not.”

11:00 a.m.
Dozens of conservative national security experts are warning that Donald Trump is unfit to be commander-in-chief.

In a letter released Wednesday evening, former Homeland Security Secretary Michael Chertoff and more than 70 other experts say they have disagreed with one another on a variety of issues but are united in their opposition to a Trump presidency.

They say Trump’s “embrace of the expansive use of torture” is inexcusable. They also object to Trump’s “hateful, anti-Muslim rhetoric” and his advocacy for waging trade wars, which they say would lead to economic disaster in a globally connected world.

“His vision of American influence and power in the world is wildly inconsistent and unmoored in principle,” they say. “He swings from isolationism to military adventurism within the space of one sentence.”

Other experts who signed the letter are Frances Townsend, former homeland security and counterterrorism adviser to President George W. Bush; Eliot Cohen, former counselor to the State Department; and Dov Zakheim, former Pentagon comptroller.

Cohen and Bryan McGrath, a retired Navy officer and managing director of The FerryBridge Group defense consulting firm, organized the letter. McGrath says he’s gratified by the large number of signatures. The letter, he says, is a “vehicle for people to say they’ve had enough.”

10:30 p.m.
New Mexico Gov. Susana Martinez is endorsing Marco Rubio’s presidential bid support from a rising Republican star that will undoubtedly boost the Florida senator’s sway among Latino voters.

Rubio mentioned Martinez’s name back in November when discussing potential running mates, but Martinez has largely shrugged off questions about higher political aspirations.

The backing from the nation’s only Latina governor comes days after Martinez refused to say whether she would support Donald Trump if he became the Republican nominee.

Martinez plans to campaign with Rubio in Kansas on Friday.

10:15 a.m.
Bernie Sanders is making trade policy a centerpiece of his efforts to win next week’s Democratic presidential primary in Michigan.

He’s trying to make the case that Hillary Clinton’s approach to trade has been wrong and that families have suffered as a result of policies she supports.

Sanders says at a news conference in Lansing, Michigan, that he and Clinton have been on opposing sides on a number of trade deals, including the North American Free Trade Agreement and normalizing trade relations with China.

Sanders is aiming for victory this coming Tuesday in Michigan and hoping to cut into Clinton’s lead among delegates.

9:55 a.m.
Dozens of conservative national security experts are warning that Donald Trump is unfit to be commander in chief.

Former Homeland Security Secretary Michael Chertoff and more than 70 others say they’re united in their opposition to a Trump presidency.

They say Trump’s “embrace of the expansive use of torture” is inexcusable. They also object to what they say is Trump’s “hateful, anti-Muslim rhetoric” and his advocacy for waging trade wars.

The letter says Trump’s vision of “American influence and power in the world is wildly inconsistent and unmoored in principle.”

Among the experts who signed on Frances Townsend, homeland security and counterterrorism adviser to President George W. Bush; Eliot Cohen, a former counselor to the State Department; and Dov Zakheim, a former Pentagon comptroller.