The first Muslim to be elected to Congress is asking Americans to sign a petition for Donald Trump to apologize to the Khan family, in an email blasted out Wednesday by the Democratic Congressional Campaign Committee.

"Trump's insults are not just an assault on one family," says the email, signed by Rep. Keith Ellison, D-Minn. "He's attacking millions of Muslims like me. And if we shrug this off as just another gaffe from Trump, folks across this country will think there is nothing wrong with this blatant discrimination."

Trump has come under widespread criticism from Democrats and Republicans alike for belittling the parents of slain Muslim soldier Humayun Khan, who was killed in 2004 in Iraq in a car bombing and earned a Gold Star for his service.

The DCCC has set up an online petition that voters can sign, asking Trump to apologize to the Khan family. It had been signed by about 20,000 people as of Wednesday afternoon.

Ellison became the first Muslim in Congress when he won his seat in 2006.

"I'm a Muslim. I'm an American. I'm a member of Congress. And I am livid after seeing Donald Trump's attack on the Gold Star Khan family," the email says.