As establishment Republicans grapple with the idea that Donald Trump may win their party's nomination for president, they continue to look for alternatives.

Mitt Romney after Speaker of the House Paul Ryan was elected in Washington, DC. (Photo by Win McNamee/Getty Images)

Few believe Ted Cruz and Marco Rubio have the ability to take Trump out, but they may deny him enough delegates to win it outright.

If there is a contested convention, delegates could draft someone not currently in the race.

The two names being floated are Mitt Romney and former New York Mayor Michael Bloomberg.

Romney is due to deliver a speech this week many view as testing the water for another run.