Three U.S. congressmen, who are also veterans, are calling for Speaker of the House Paul Ryan to end his endorsement of Republican Party Presidential Nominee Donald Trump.

Rep. Ruben Gallego (D-AZ), Rep. Seth Moulton (D-MA), and Rep. Ted Lieu (D-CA) wrote a letter to the speaker of the house.

Yesterday during his show, Wolf Blitzer quoted the letter as saying, “As veterans who previously served on active duty, we are horrified by Republican presidential nominee Donald Trump’s slander of parents whose son died serving our country. We were heartened by your first instinct, which was to not endorse Mr. Trump. We respectfully request that you follow what we believe your heart is telling you and withdraw your endorsement of him now.”

Rep. Lieu, who is also a Colonel in the Air Force Reserve, told Blitzer that Trump lacks the qualities to be the president of the United States.

But most importantly for Lieu, Trump lacks the qualities to be the commander-in-chief of the U.S. military and Lieu fears that Trump’s quick temper will lead to catastrophic results.

Lieu told Blitzer, “My biggest concern is that in November we’re not just electing a president, we’re electing a commander-in-chief. And a president who proposes stupid laws, for example, such as banning Muslims, Congress can stop that or the courts will strike it down. There are checks and balances. But when a commander-in-chief decides to take action to defend America, such as launching airstrikes or God forbid launching a nuclear first strike, that person needs to have temperament, judgement, and knowledge… Donald Trump fails all those elements of leadership.”