He is set to travel to Iowa on Sunday, where he intends to spend three days in the state introducing himself to voters who will open the nominating contest early next year.

Mr. Perry is the longest-serving governor of Texas, having been elected to three terms and having held the position for more than 10 years. He is known as a fierce and skilled campaigner, as well as a prodigious fund-raiser. In past campaigns, he has eked out victories and also come from behind to win by large margins. “He becomes immediately one of the top three candidates, and he fills a vacuum — of someone who is a conservative, who has credibility and can speak to the fiscal conservative, anti-big-government and anti-Washington crowd, but he’s also a social conservative,” said Matthew Dowd, a former strategist for President George W. Bush.

What Mr. Perry does in the coming weeks will be the real test of his candidacy, said Republicans who were waiting to see if he could withstand the scrutiny that comes with a presidential campaign.

“He either gets in and gets through the gantlet of the first month or so and consistently moves forward and wins the nomination, or he’s got this terrific flameout,” Mr. Dowd said. “There’s no middle ground.”

Mr. Romney has positioned himself as the candidate with real-world experience who can turn the economy around and create jobs, and Mr. Perry will compete with him on that front, making a case that his policies of low taxes and light regulation have helped Texas post a strong record of job growth at a time when most of the nation is struggling.

“We’ll create the jobs and the progress needed to get America working again,” Mr. Perry told the crowd in Charleston. “And I’ll promise you this: I’ll work every day to make Washington, D.C., as inconsequential in your life as I can.”

Democrats challenged Mr. Perry’s efforts to portray his policies as having benefited Texas.

“He’s cutting services in order to maintain really low tax rates, and so many of the jobs he’s created are these minimum-wage jobs, not these living-wage jobs,” said Representative Lloyd Doggett, Democrat of Texas. “I think he has, as they would say here in Texas, plenty of ’splaining to do about his positions.”