U.S. television networks project former Massachusetts governor Mitt Romney has won the Republican presidential primary election in the eastern state of Maryland.

Tuesday's win brings him another step closer to winning enough delegates to become the Republican Party's choice to take on President Barack Obama in the November general election.

Romney is also hoping for wins in Washington, DC and the midwestern state of Wisconsin.

Romney already has about half the number of delegates needed to win the nomination. He has also been endorsed by such major Republicans as former President George H.W. Bush.

But Romney's Republican challengers — Rick Santorum, Newt Gingrich, and Ron Paul — have given no signs they are ready to drop out of the race.

Santorum, a former U.S. senator from Pennsylvania, is hoping his home state's primary later this month will give him a badly needed boost.

Meanwhile, President Obama is already anticipating a November showdown against Romney. In a speech to newspaper executives Tuesday, Mr. Obama denounced a Republican budget plan backed by Romney, saying it would impose “a radical vision” on the country.

Vice President Joe Biden and Secretary of State Hillary Clinton have also criticized Romney and Democratic “attack ads” targeting Romney also have been appearing on radio and television.