UPDATE 2-Clinton presses re-vote case in Michigan

(Adds comment from Obama, paragraphs 8-9)

By Jeff Mason

DETROIT, March 19 (Reuters) - Democrat Hillary Clinton pressed on Wednesday for a new vote in Michigan that could be crucial to her aspirations in the tight battle with Barack Obama to be the party's presidential nominee in November.

"I am here for one simple reason: to make sure Michigan's votes are counted and your voices are heard in this election," the New York senator said in a hastily arranged visit to the state.

Democratic nominating contests in Michigan and Florida in January were invalidated by the national party because both states violated party rules. Both states were denied delegates to the August party convention that picks the nominee.

Clinton, a former first lady, won both contests and needs the delegates in those states if she hopes to overcome the lead Obama has built up.

Clinton urged rival Obama, a senator from Illinois, to give his backing to a proposal that would allow the state to hold a new Democratic contest in Michigan.

"Senator Obama speaks passionately on the campaign trail about empowering the American people. Today I am urging him to match those words with actions," she said.

"We need to either count the votes that have already been cast in Michigan and Florida or have new full and fair elections so that we can have your voices and your votes counted," she said to applause.