NBC, CBS and CNN projected Romney an easy winner over Newt Gingrich and Rep. Ron Paul. CNN said with 50 percent of the precincts reporting, Romney, a former Massachusetts governor who is the presumptive GOP nominee, had 57 percent of the vote to 26 percent for Gingrich, a former U.S. House speaker from Georgia, and 11 percent for Paul, the Texas congressman.
Gingrich, strapped for campaign cash, invested a lot of time in Delaware, hoping to snatch a state win. He has only won two state primaries -- Georgia and South Carolina -- and needs five states to be on the ballot during the Republican National Convention in Tampa, Fla., in August.
Romney went into the day's series of five primaries with 695 delegates, CNN said. He needs 1,144 to win the party's nomination. Gingrich had 141 delegates and Paul 72.
There were 17 delegates up for grabs in Delaware. Romney also won in Rhode Island, with 19 delegates, and Connecticut, with 28. Republicans also were voting in New York (95 delegates) and Pennsylvania (72 delegates).
Romney's path to the nomination opened up when his closest rival, former U.S. Sen. Rick Santorum of Pennsylvania, exited the presidential race April 10.
Notable deaths of 2014 [PHOTOS]