w if he were president. Fellow GOP presidential hopeful Newt Gingrich faced a backlash earlier after publicly criticizing Ryan's Medicare proposal. "If we don't make any changes, then Medicare won't be there for the next generation and that's unacceptable to me. So I appreciate what Paul Ryan has done," Romney told reporters in Ankeny after visiting an agricultural software company. "I'm going to have my own plan." Romney was making his first visit to Iowa since formally beginning to explore a second bid for president. He plans to announce his 2012 candidacy next week in New Hampshire. He finished second in the state's leadoff presidential caucuses last time and is expected to wage a more limited campaign. His carefully planned day hit a snag during an appearance in Des Moines. A fire alarm triggered by burnt microwave popcorn, forced the evacuation of a museum during a question-and-answer session that followed Romney's speech. That sent Romney and the roughly 200 people attending the event onto the street outside. Romney, who served one term as Massachusetts governor, is stressing as he approaches the 2012 bid his business and private sector background as an investment company executive and CEO of the 2002 winter Olympics. Aides said Romney did not develop this niche in 2008 and at commented too often on less familiar cultural issues, which hurt him in socially conservative Iowa. Romney had supported abortion rights, gay rights and gun control as governor. Romney returned to Iowa focused squarely on the economy. "What I know and what I've spent my life doing is particularly relevant right now," he told the 200 people at the museum event, including Republican activists and past supporters. In Des Moines, he set himself up as the best alternative to President Barack Obama on economic issues. He said the Democrat's legislative agenda, including the 2010 health care law, had sown uncertainty at a time investors needed encouragement. "It's time to have a president how to create jobs, because he's had one, and knows how the economy works for t