Updated 9:31  p.m. | Mitt Romney easily won the Maryland primary tonight, putting the finishing touches on his quest for the Republican presidential nomination.

Continuing his string of wins in moderate Northeastern states, the former Massachusetts governor did well enough in exit polls that the Associated Press called the race less than 15 minutes after polls closed at 8 p.m.

Updated 8:46 p.m.

Romney was projected to win a primary in Washington, D.C., by multiple news outlets before 9 p.m., when polls close in Wisconsin.

Updated 9: 31 p.m.

News networks also called Wisconsin for Romney around 9:30 p.m., essentially ending the Republican primary season.

In a defiant speech, former Pennsylvania Sen. Rick Santorum vowed to stay in the race.