June 9 (Bloomberg) -- The next president plans to issue new policies to address global warming, overhaul immigration laws, advocate more government transparency and close the U.S. detention center at Guantanamo Bay.

It may sound like a risky prediction five months before the election. Presumed Democratic nominee Barack Obama and his Republican rival, John McCain, are diametrically opposed on the biggest issues facing Americans, including extending President George W. Bush's tax cuts, ending the Iraq War, overhauling health care and appointments to the Supreme Court.

Yet on the most significant second-tier policy questions, the two are surprisingly often in agreement, probably more so than any major-party candidates since 1976.

``They are peculiarly connected,'' said Stephen Hess, a scholar at the Washington-based Brookings Institution who served as a speechwriter for President Dwight D. Eisenhower. In part, that's because ``one is following the precepts of his party and the other is going off in another direction,'' Hess said.

McCain is a ``maverick'' who often bucks Republican principles, Hess said. His emphasis on issues may change as he tries to appeal more to his party's conservative base and separate himself from Obama, Hess said.

For the moment, though, they display similarities that make them appealing to independent voters, Hess and other political historians said.

`Agent of Change'

``The image they're presenting is the same -- they're the agent of change, the reform candidate, they're the one who will reach out to the other party,'' said Julian Zelizer, a history and public affairs professor at Princeton University in New Jersey.

McCain and Obama have both been at odds with Bush on the treatment of suspected terrorists and closing the U.S. camp at Guantanamo Bay, Cuba, which the president can accomplish by executive order.

McCain, 71, served as a prisoner of war in Vietnam and has fought as an Arizona senator to outlaw interrogations that might be construed as torture. In a May 2007 interview, McCain said one of the biggest differences between him and his rivals for the Republican nomination was ``every one of them wants to torture people. It's amazing.''

`Highest Standards'

Obama, 46, an Illinois senator, has been equally critical of U.S. detention policies and says too many prisoners languish in Guantanamo without fair trials.

``We can set the highest standards around the world for human rights and rule of law and close Guantanamo and restore habeas corpus,'' Obama said while campaigning in North Carolina last month. ``Because you'll have a president who has taught the Constitution and believes in the Constitution.''

Both are champions of more disclosure and regulations for politicians. McCain's name is affixed to landmark 2002 legislation that overhauled campaign-finance laws. Obama last year helped push through the biggest changes in congressional ethics rules in a generation.

``Government reform'' is one of the highlighted issues on McCain's campaign Web site, where he promotes his fight for an independent ethics office in Congress among other things. Obama rails against closed-door meetings and says he would hold negotiations on his health-care plan on C-Span television.

In addition, McCain is co-sponsoring legislation that Obama introduced with Oklahoma Republican Senator Tom Coburn to expand the information available on government spending.

Climate Change

McCain and Obama are also devoted to fighting global warming, an issue that earned Bush criticism after he rejected the 1997 Kyoto Protocol and questioned the science behind climate change. McCain devoted a campaign swing in May to the topic, pledging to be the true ``environmental president.''

``There's a long-standing, significant, deep and strong difference on this issue between myself and the administration,'' McCain said on May 13 in Washington state.

Obama routinely talks about global warming, pledging to help develop alternative energies and create ``green jobs.''

Neither McCain nor Obama was present June 6 when Senate Republicans blocked climate-change legislation that would have cut greenhouse gases and established a European-style emissions- credit system.

One topic where the candidates do agree with Bush is on the need for an overhaul of immigration laws. They would all support some sort of path to citizenship for illegal aliens, a move immigration foes deride as ``amnesty.''

Republican Resistance

Bush's attempt to get an immigration package through Congress stalled last year, and some of the stiffest resistance came from his own Republican Party.

McCain and Obama also line up in support of allowing Americans to buy cheaper medicines from Canada -- a stance opposed by the pharmaceutical lobby and many members of McCain's party.

They disagree, however, over the broader question of fixing the health-care system. Obama supports a major program to provide universal coverage; McCain favors tax credits to make insurance more affordable and some federal aid.

Their similarities may have much to do with the basic middle-of-the-road beliefs of many Americans, said Clyde Wilcox, a government professor at Georgetown University in Washington.

``America is a moderate country, and many of our elections have involved candidates moving to the middle,'' Wilcox said. ``But the devil is often in the details.''

To contact the reporter on this story: Kristin Jensen in Washington at kjensen@bloomberg.net

Last Updated: June 9, 2008 00:01 EDT