US Republican White House contender Mitt¹ Romney has pulled off a double win in the Michigan and Arizona primaries.

美国共和党白宫竞选人米特·罗姆尼在密歇根州和亚利桑那州的总统预选中获双胜。

Mitt Romney stressed key themes in his victory speech: "More jobs, less debt, smaller government"
"We didn't win by a lot, but we won by enough and that's what counts," Mr Romney said in Michigan.

In Arizona, he leads with 49% of votes, and heads Rick Santorum in Michigan by 41% to 38% with 85% counted.

Michigan was seen as vital for Mr Romney, born in the state where his father was governor, but had struggled to win over conservative voters.

Rick Santorum addressed supporters in Michigan, moments after he reportedly called Mr Romney to concede（承认，退让） defeat, thanking voters for their support.

Former House Speaker Newt Gingrich and Texas Congressman² Ron Paul did not compete in Arizona and Michigan, focusing on contests scheduled for next week.

Mr Gingrich was on course to win 16% in Arizona, with Mr Paul on 8%.

In Michigan, Mr Paul has won 12% of the vote, with 7% for Mr Gingrich.