Mitt Romney Wins Michigan Primary

Mitt Romney added to his lead in the race for convention delegates Tuesday with a win in the Arizona Republican presidential primary. Romney also won the Michigan primary, but it was unclear who would win the most delegates in that state.

The former Massachusetts governor won all 29 delegates in Arizona, a rare winner-take-all state. Romney also won at least five delegates in Michigan, where former Pennsylvania Sen. Rick Santorum also won at least five delegates.

Texas Rep. Ron Paul and former House Speaker Newt Gingrich were shut out, with 20 delegates left to be awarded in Michigan.

Michigan awards 28 of its 30 delegates based on results in individual congressional districts. Candidates get two delegates for each congressional district they win. The final two delegates are awarded proportionally, based on statewide results.

Both Romney and Santorum were leading in multiple congressional districts, with more than 60 percent of the precincts reporting.

In the overall race for delegates, Romney has 157 delegates, including endorsements from Republican National Committee members who automatically attend the party's national convention and can support any candidate they choose.