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An incumbent president seeking re-election can have a clear advantage, especially in foreign policy.

With a powerful military and vast diplomatic corps at his disposal, President Bush can make things happen. As just one of 100 senators, John Kerry (search) can't.

Unlike Kerry, Bush gets to play the role of statesman. He'll be invited to address the U.N. General Assembly (search) next month, not Kerry.

Will Bush thwart Kerry's stab at history with an October surprise?

Foreign policy moves also can be an albatross for a president seeking another term. Just ask Jimmy Carter (search). Will Iraq do to Bush what Iran did to Carter?

Forty years ago, Democratic President Lyndon Johnson (search) was able to parlay a minicrisis off the coast of Vietnam to his benefit against his Republican opponent, Sen. Barry Goldwater (search) of Arizona.

Johnson claimed that two American destroyers had come under fire from North Vietnamese torpedo boats in the Gulf of Tonkin. No harm was done, but an almost unanimous Congress gave Johnson the authority to "take all necessary measures" to repel armed attacks against U.S. forces.

For a week, the political playing field was decidedly uneven. Johnson came across as an engaged commander in chief; there wasn't much Goldwater could do about it. He lost badly in November, but for reasons that went beyond the tiff in Vietnamese waters.

Although it was not clear at the time, Johnson was able to use the Gulf of Tonkin resolution as justification for a major buildup of U.S. forces in Vietnam after his inauguration.

In late October 1972, President Nixon was in a re-election struggle with Sen. George McGovern, D-S.D. A week before the balloting, Nixon authorized national security adviser Henry Kissinger to say "peace is at hand" in Vietnam. It was welcome news to a war-fatigued nation, which gave Nixon a big mandate days later.

Kissinger's bold prediction of impending peace was far off the mark; the heaviest bombing of the war was to occur starting just before Christmas 1972, much too late to help McGovern, who opposed the war. A peace deal was finally struck in late January, but peace still was not at hand for the Americans until the last ones abandoned Saigon in 1975.

Nixon had been buttressing his reputation among voters as worldly wheeler-dealer throughout 1972, making historic visits to China and Russia, among other initiatives.

President Reagan no doubt had his re-election in mind when he visited China in April 1984. He also quieted an outcry over his pugnacious Central America policy by authorizing peace talks that June. Once Reagan's defeat of challenger Walter Mondale was in the bag, he called off the talks.

For almost a half-century, Fidel Castro has proved to be a handy election-time target. Trade with Cuba was curtailed two weeks before the 1960 election. The first President Bush signed sanctions-tightening legislation against Cuba a week before his failed re-election bid in 1992.

With President Clinton's blessing in the election year of 1996, Congress again tightened the screws on Cuba. And this past May, it was no surprise when the current President Bush hardened sanctions against the island still further.

Kerry is no doubt aware of how previous presidents have used foreign policy to keep challengers off-balance during election campaigns.

At the same time, he knows that foreign issues can backfire on an incumbent seeking a new mandate. In 1980, the Iran hostage crisis contributed to the wreckage of Carter's presidency. His attempt at a military hostage rescue operation six months before the election failed dismally.

Bush obviously has his hands full with problems abroad, particularly the continuing violence in Iraq. And a deadly pre-election terrorist attack on U.S. soil almost certainly would have an effect on the November balloting; it is not clear which candidate would benefit.

Intelligence reform is another issue on which Bush and Kerry already are seeking voter favor before November. It may be another example of the incumbent having the advantage. Bush can act. Kerry can only react.