By Shailagh Murray

MIAMI -- Sen. Barack Obama outlined a comprehensive Latin America policy aimed at bolstering diplomacy, security and investment in the region, asserting before a Cuban American audience here, "The situation has changed in the Americas, but we've failed to change with it."

Obama's speech to the Cuban American National Foundation came four days after Sen. John McCain addressed the Miami Cuban community and advocated a continued hard-line approach to the Havana regime, by enforcing the existing trade embargo and travel restrictions. Obama devoted a large portion of his speech to Cuba and called for a starkly different approach, reiterating his pledge to lift travel and money transfer restrictions and to negotiate directly with the Cuban government.

McCain's campaign responded to Obama's speech hours before he delivered it, accusing him of advocating an "unconditional summit" with Raul Castro's Communist government. The heated exchange underscored the battle line that Cuba has become between the two likely nominees in a swing state that could decide the election.

Obama brushed off the McCain broadside. "Now I know what the easy thing is to do for American politicians. Every four years, they come down to Miami, they talk tough, they go back to Washington, and nothing changes in Cuba," he told the crowd. "That's what John McCain did the other day. He joined the parade of politicians who make the same empty promises year after year, decade after decade."

"Let me be clear," he continued. "John McCain's been going around the country talking about how much I want to meet with Raul Castro, as if I'm looking for a social gathering. That's never what I've said, and John McCain knows it. After eight years of the disastrous policies of George Bush, it is time to pursue direct diplomacy, with friend and foe alike, without preconditions."

Obama asserted, "I will never, ever, compromise the cause of liberty." But unlike McCain, he added, "I would never, ever, rule out a course of action that could advance the cause of liberty."

He said he would maintain the embargo as leverage to compel the Cuban government to take "significant steps towards democracy," beginning with the freeing of political prisoners. "That's the way to bring about real change in Cuba -- through strong, smart and principled diplomacy," Obama said.

After the speech, the McCain campaign fired off a recap of previous statements where Obama criticized the embargo, casting him as a flip-flopper.

"By changing his position in front of Cuban Americans to support the embargo that he used to oppose, Barack Obama is engaging in the same political expediency that he railed against in his speech," said spokesman Tucker Bounds. "This same tired type of political flexibility shows Barack Obama's weak leadership on an important issue."

Obama also proposed a new regional energy initiative that would allow U.S. industrial emitters of carbon to offset a portion of their costs from a new cap and trade system by investing in low carbon energy projects in Latin America and the Caribbean. He called for investments in "clean coal" technology and other alternative sources, like wind and solar, and said he would establish an "Energy Corps" to dispatch clean energy experts to the region.

He said he would increase resources to battle crime and drug trafficking in Latin America, and advocated more development assistance and Peace Corps volunteers. Obama said he would resist trade deals that give short shrift to workers and described the "backbreaking inequality" that persisted, despite the vast resources of many Latin American countries. He would erase Cold War-era distinctions between governments, he added, judging them based on how they treated their people.

"The person living in fear of violence doesn't care if they're threatened by a right-wing paramilitary or a left-wing terrorist; they don't care if they're being threatened by a drug cartel or a corrupt police force. They just care that they're being threatened, and that their families can't live and work in peace. That is why there will never be true security unless we focus our efforts on targeting every source of fear in the Americas," Obama said.

"There's an overarching theme here, which is re-engagement," said Robert Gelbard, a former U.S. ambassador to Bolivia, who advised Obama on the speech. "The United States has been AWOL ... for these last eight years."