Carlos Osorio, Associated Press
Republican presidential candidate, former Massachusetts Gov. Mitt Romney waves at his election night party in Novi, Mich., Tuesday, Feb. 28, 2012.

NOVI, Mich. — A beaming Mitt Romney is focusing on President Barack Obama after victories in Michigan and Arizona's primaries, saying Obama has failed to lead the American economy.

Romney says it doesn't matter that the vote was close in his home state of Michigan, where he held off a strong challenge from former Pennsylvania Sen. Rick Santorum. He says a win is a win even though it was a narrow win. The former Massachusetts governor also won handily in Arizona.

Romney says his economic plan, which he unveiled in Michigan this week, will help American recover from Obama's leadership. He says the stakes are high in the election. He says it's about "saving the soul of America."