Mitt Romney in a long-awaited immigration address on Thursday vowed to overturn President Obama's directive to stop the deportation of young illegal immigrants, saying he would replace that "stopgap" measure with comprehensive, long-term immigration reforms.

Romney, speaking to the National Association of Latino Elected and Appointed Officials conference in Orlando, charged that Obama's policy shift was politically motivated and that he had put many other priorities ahead of immigration reform before being "seized by an overwhelming need to do what he could have done on day one."

"I will put in place my own long-term solution that will replace and supersede the president's temporary measure," Romney said.

Romney, who pressed for get-tough immigration measures while seeking the Republican presidential nomination, offered more moderate proposals Thursday, including allowing illegal immigrants who served in the U.S. military legal status. He called for a speedier application process for those seeking work visas and the lifting of caps on the number of visas that can be issued.

He promised to complete a 2,000-mile fence along the U.S.-Mexico border to curtail the flow of illegal immigrants into the United States.

Less clear, however, was what exactly Romney would do with the millions of other illegal immigrants now living in the United States, an ambiguity the Obama campaign said proved Romney's unwillingness to compromise on an issue that has overwhelming support in the Hispanic community.

"In front of an audience of Republican primary voters, he called the Dream Act a 'handout' and promised to veto it," said Obama campaign spokeswoman Gabriela Domenzain. "We should take him at his word that he will veto the Dream Act as president."

Romney's remarks came nearly a week after Obama announced that his administration would stop deporting illegal immigrants brought to the United States before they turned 16, are now younger than 30, have no criminal history, graduated from an American high school and have been in the country five consecutive years.

Immigration has proven a politically difficult issue for Romney, who is trying to reassure a conservative base that he is appropriately tough on illegal immigration while not alienating independent and Hispanic voters who could swing the election. He suggested during the primary that illegal immigration could be regulated through "self-deportation."

His position grew more difficult when some prominent Republicans, including Sen. Marco Rubio of Florida, called on the party to be more accommodating to Hispanics, the nation's fastest-growing voting bloc.

As he has on so many issues, Romney talked about immigration through the prism of the economy.

"The middle class has been crushed under President Obama," he said. "Over two million more Hispanics are living in poverty today than the day President Obama took office."

But some advocates for a pathway to citizenship for illegal immigrants said Romney had produced nothing more than a hazy road map for reform that has eluded lawmakers for decades.

"Platitudes about legal immigration policies were expected," said Frank Sharry, executive director of America's Voice, an immigration advocacy group. "He can't continue to dodge the key questions: Does he still think that 'self-deportation' is the right approach for their parents and the millions of other immigrants living and working here without papers?"

Obama will address the same Hispanic group Friday.