The war in Iraq, U.S. relations with Iran and the state of the economy are all expected to be major factors in next year's presidential campaign. In the fourth part of his series on the 2008 election, National correspondent Jim Malone looks at the issues likely to dominate the debate.

Many experts predict Iraq will be the top issue in the 2008 campaign, much as it was when President Bush won re-election in 2004.

"The war is the overriding issue," said Allan Lichtman, a presidential historian at American University in Washington, D.C. "Whenever there is a war that becomes the issue for a generation. Unless of course there is a recession and that might overshadow the war, but nobody knows whether that is going to happen or not."

Some Republicans believe the improved security situation in Iraq could help whoever becomes the Republican Party's presidential nominee next year. But Lichtman believes the Democratic nominee will have an advantage with independent voters going into the 2008 campaign.

"The recent situation may have slightly improved for the administration, but that has mainly moved Republicans," he said. "It has not moved Democrats at all and has not caused much movement among independents. And Republican votes [alone] are not going to be good enough for a presidential candidate [to win] in 2008."

Iraq remains a central issue in the battle for the Democratic Party nomination where Senator Hillary Clinton of New York continues to lead the field in public opinion polls.

Some of Clinton's rivals question her initial support of the war.

"It has not faded as an issue among Democratic activists," said Stephen Wayne, a professor of government at Georgetown University in Washington. "It has faded as a salient issue among the country for the simple reason that the Congress is divided and the Democrats do not seem to be able to win any votes and there seems to be a pessimism that there is no way they can stop Bush, and that the only way to change Iraq is when we have a new president."

Iraq, Iran and other foreign policy issues are getting a lot of attention on the campaign trail, especially in early voting states like Iowa and New Hampshire.

"The war in Iraq and the war on terror and Iran and nuclear weapons are things that are looming in front of people and they are concerned about it," said Arthur Sanders, a political scientist at Drake University in Iowa. "You know, when candidates go to these [voter] forums, they get asked about that."

Those same issues are being discussed in New Hampshire as well. But Democrats there are also concerned with supporting a candidate who can win the general election in November of 2008.

"So, you see Iraq, but also typical Democratic concerns such as health care, for example, are on the list," said Dante Scala, who lectures on politics at the University of New Hampshire. "But given that candidates wind up having more or less similar positions on a host of issues, I think it does come down to factors such as personality and perceived electability."

Many experts believe the mix of issues at the moment favors the Democrats.

"They [Democrats] have many advantages, not least that we have had one party in power for eight years," said Larry Sabato, who directs the Center for Politics at the University of Virginia. "Americans like to change, normally, after eight years, but we do not always do it. Second, there is no question that the president's unpopularity, which stems mainly from Iraq but also from (the response to Hurricane) Katrina and other events is going to be an albatross around the neck of any Republican nominee."

But Republican strategists say that the Democrat's advantage on the issues could change if the focus of the campaign turns to national security and the war on terror.

"The way that they [Republicans] might [gain an advantage] would be to paint a Democrat as being weak or inexperienced on foreign policy in general, not just Iraq, and the war on terror," said John Fortier, who monitors presidential politics at the American Enterprise Institute in Washington.

Illegal immigration is another issue that could ignite passions in both the early primaries and in the general election campaign.

"Immigration has been an issue that has erupted periodically, and I think as an undercurrent is quite important," said Steffen Schmidt, a professor of political science at Iowa State University. "It is not as visible as some of the other issues on a day to day basis, but I know from talking to many activists that it is very, very important."

Recent national surveys suggest the war in Iraq and domestic concerns about health care, the economy and jobs top the list of voter priorities as the election cycle approaches.

In our final report in the series, a look at the possibility of a major third party candidate in next year's election.