Every cloud has a silver lining.

Congressional Democrats are hoping that axiom rings true if President Bush wins a second term today.

Such a scenario would set up a so-called “six-year itch” election in 2006, which, if history is any guide, will hand major losses to the president’s party.

While no party officials or Democratic strategists would discuss the possibility on the record — for fear of offending the unswervingly optimistic House Minority Leader Nancy Pelosi (Calif.) — most observers interviewed for this article are well aware of the historical precedents.

Since World War II, there have been five elections during the sixth year of an administration’s tenure in the White House — 1958, 1966, 1974, 1986 and 1998 (1966 was the sixth year of Democratic rule under John Kennedy and Lyndon Johnson; 1974 was year six of the Richard Nixon-Gerald Ford continuum).

In those elections, the president’s party lost an average of 29 House seats and six Senate seats.

History is not entirely conclusive on the matter, however, as the most recent second-term, midterm election — in 1998 — saw Democrats pick up five House seats and preserve the status quo in the Senate even with President Bill Clinton in office.

Despite that hiccup, Democrats remain confident a second Bush term would deliver them major gains in Congress.

“The history of six-year itches is a bit like Xanax to help Democratic House and Senate operatives sleep well if Kerry loses,” said one Democratic consultant, who spoke on the condition of anonymity.

Another consultant argued that the presidential race is a battle of personalities, with the Bush agenda playing a mostly secondary role in voters’ minds.

“Where you will have the real election about the Bush agenda is 2006,” said the consultant.

With Republicans a solid favorite to retain their House majority in the 109th Congress and retaining a slight edge in the battle for the Senate, a second Bush term would force a party in control of all three levers of government to solve the looming budget crisis as well as attempt to reform the Social Security system before it goes belly up.

“Given the war and the economy, unless things gets radically better in the next two years, Republicans will have big losses,” said a Democratic consultant, who also spoke on the condition of anonymity for fear of retribution. “The president has made it clear that he is not changing his agenda. His agenda has got him to a 50-50 race.”

Though Republicans are well aware of past six-year-itch elections, they argue that recent history seems to point to a change in the trend.

“We have had two midterm elections where what was predicted in terms of the historical norm didn’t happen,” said Terry Nelson, field director at the National Republican Congressional Committee during the 1998 cycle and now national political director of the Bush campaign.

Not only did Democrats pick up House seats in 1998, but in 2002 — Bush’s first midterm election — Republicans also won back control of the Senate and added six House seats, an unprecedented gain.

Nelson also pointed out that the 2001 Congressional redistricting process, which was aimed at solidifying incumbents of both parties, ensured that even a major swing in the national mood is not likely to set off a large switch in the number of House seats each party controls.

“Given the stability of these seats, stability not from national politics but from the way the lines are drawn, you would not see a return to significant turnover,” Nelson predicted.

Despite pledges by House Democrats to expand the playing field this cycle, roughly 35 seats are being contested by the parties, just 8 percent of the 435 House seats up.

The number of contested races has fluctuated little since the 1994 election when Republicans won 52 Democratic-held seats, taking back House control in the process.

Carl Forti, communications director at the NRCC, said that starting with the 2000 election his organization has concentrated on structuring races around local issues.

“Building around local issues helps insulate you against historical trends like this,” he said.

Six years ago Democrats argued that history was no guide because voters were angry at the Republicans’ dogged pursuit of impeachment charges against Clinton.

Impeachment certainly played a role in the 1998 elections, though whether it was the prime reason for the break with the results of past six-year-itch elections is impossible to know.

Regardless of the ultimate impact of impeachment, however, the 1998 election did show that no cycle exists in a vacuum and extenuating circumstances complicate any effort to rely solely on history as a predictor.

In 1958, President Dwight Eisenhower’s chief of staff, Sherman Adams, resigned his post after admitting to taking gifts from people seeking favors from the White House. Adams’ admission came less than two months before Republicans lost 48 House seats and 13 Senate seats.

In 1974, President Richard Nixon had just resigned, and his party lost 49 House seats and 4 Senate seats.

Again in 1986, the Iran-Contra imbroglio dominated the news; Republican losses were more muted, but the GOP still saw its number decline by five seats in the House and eight seats in the Senate just two years after President Ronald Reagan carried 49 states in his bid for a second term.