CARTAGENA, Colombia - President Barack Obama is making a rare foray into national politics while abroad, taking a jab at the immigration stance of his likely rival in November's presidential election.
As he struggles with declining popularity among the key Hispanic electorate that helped put him over the top in 2008, Obama vowed to fulfill his promise of immigration reform in the first year of his second term, providing a path to citizenship for nearly 12 million undocumented immigrants.
"The challenge we've got on immigration reform is very simple. I've got a majority of Democrats who are prepared to vote for it, and I've got no Republicans who are prepared to vote for it," Obama told Spanish-language Univision television on his quandary with Congress.
The interview was conducted Friday after the president arrived in Colombia for the Summit of the Americas, and was released Saturday.
Republicans control the House of Representatives, while Democrats only have a slim majority in the Senate, where Republicans can using blocking tactics thanks to their numbers.
"It's worse than that. We now have a Republican nominee who said that the Arizona laws are a model for the country... and these are laws that potentially would allow someone to be stopped and picked up and asked where their citizenship papers are based on an assumption," Obama continued.
He referred to Romney as the "nominee" even though the Republican nomination contest is not yet officially over ahead of the head-to-head general election battle between the conservative party's pick and Obama, who is seeking a second four-year term.
Arizona, which borders Mexico, was the first of several US states to demand that immigrants carry identity documents to justify their presence on US soil. A federal judge has blocked some of its toughest provisions.
Obama called the law "very troublesome."
"This is something that the Republican nominee has said should be a model for the country. So what we need is a change either of Congress or we need Republicans to change their mind," Obama said.
His statement marked a rare discussion of domestic politics from abroad by Obama as he gears up for a likely hard-fought general election campaign.
The president, who released his tax return Friday as he has for each year going back to 2000, also used the occasion to launch an attack on Romney, a multi-millionaire venture capitalist he is trying to portray as oblivious to the economic struggles of middle class American families.
The former Massachusetts governor has released his return for 2010 and an estimate of his taxes for 2011, but has yet to do the same for previous years, including when he worked at the investment firm he founded, Bain Capital.
"It's important for any candidate in public office to be as transparent as possible, to let people know who we are, what we stand for," Obama said. "I think that this is just carrying on a tradition that has existed throughout the modern presidency."
Obama's return showed he earned nearly US$800,000 (S$997,500) last year and, paid an effective federal tax rate of 20.5 per cent (US$162,074).
Around half of Obama's income came from his presidential salary of US$400,000 and the rest was from income from his bestselling books. He and First Lady Michelle Obama donated US$172,130 to charity, or about 22 per cent of their adjusted gross income.
In 2010, Romney paid a lower tax rate than many middle class Americans - 13.9 per cent on income of US$21.7 million. His estimated income from 2011 was US$20.9 million and his fortune is estimated at about US$250 million.
Because most of his income was from investments and not salary, Romney is subject to different rules than most people, and is taxed at a lower rate than many middle class Americans pay on their annual income.
Obama contends that such treatment of the wealthy is unfair, and is pushing a proposal called the Buffett rule, which would require people earning more than US$1 million a year to pay 30 per cent in taxes.