Updated at 12 a.m. ET
(CBS News) Republican presidential contender Mitt Romney on Tuesday night came one step closer to securing the GOP nomination with a victory in Maryland, giving him more than half of the delegates needed to win the nomination.
With polls closed and 1,741 of 1,892 precincts reporting, Romney carried 49 percent of the vote, while Rick Santorum took 29 percent. Newt Gingrich won 11 percent, while Ron Paul took 10 percent.
Romney also won the District of Columbia primary and is the projected winner in the .
With his victory in Maryland, Romney won 34 more delegates, according to CBS News estimates -- putting him past the half-way point to the 1,144 delegates needed to win the GOP nomination outright.
CBS News exit polling showed Romney winning the support of various voting blocs in Maryland: About half of male voters and half of female voters backed the former Massachusetts governor. Romney essentially tied with Santorum for the support of "very conservative" voters, but he won the support of conservative voters overall.
Romney easily won among voters who named the economy as the most important issue, as well as among voters who were primarily interested in defeating President Obama in the fall.
About four in 10 Maryland voters said Romney's positions are not conservative enough, but more (about half) say they are about right. A third of voters say Santorum's issue positions are too conservative.
There are a total of 92 delegates at stake Tuesday, with 37 coming from Maryland, 16 coming from Washington and 39 from Wisconsin. The Maryland and D.C. primaries were closed to Republicans while Wisconsin held an open primary.
Romney's victory was expected in Maryland, a state that is reliably Democratic in presidential general elections. More focus has fallen on the politically-charged state of Wisconsin.
Before Tuesday night's primaries, Romney had accumulated 559 delegates, according to CBS News estimates, while Santorum had 243, Gingrich had 128, and Paul had 45.