By Bob Benenson, CQ Politics Editor

Lost in the fuss over next week’s Super Tuesday presidential contests is the fact that the 2008 congressional campaign also has its official kickoff that day, with primaries in Illinois. Not that this event is being greeted with enthusiasm by many Republicans, who appear desperate to hold the White House to counteract the near-certain extension of the majorities Democrats won in both the Senate and the House in 2006.

The strong edge with which the Democrats enter the contest for congressional control is evident in CQ Politics’ ratings of the 35 Senate races and 435 House races.

This advantage is reflected in fundraising totals reported throughout the campaign run-up year of 2007 by the Democratic Senatorial Campaign Committee and the Democratic Congressional Campaign Committee, which exceeded by wide margins those amassed by the counterpart GOP Senate and House political units, the National Republican Senatorial Committee and the National Republican Congressional Committee (NRCC).

It also is evident in national poll numbers that show the public is deeply disenchanted with the Democratic-controlled Congress — but still blame the Republicans more than the Democrats for the policy gridlock about which they complain. When asked which party they would rather see in charge of Congress, respondents to the most recent polls favored the Democrats by a wide margin.

But perhaps nothing better symbolizes the upper hand the Democrats have nine months before Election Day than the lopsided imbalance in the number of seats left open by incumbents who are retiring or seeking other offices.

Five Republican members of the U.S. Senate will retire rather than pursue re-election in a year in which the GOP, overall, must defend 23 of their seats. There are 12 Democratic incumbents up for election — and all 12 are seeking re-election.

On the House side, 24 Republican incumbents are relinquishing their seats compared to just five Democrats. And that doesn’t even include the five GOP members who have resigned (or soon will) from their House seats early: two to assume statewide offices, and three who simply left to pursue other career endeavors.

There has been such a recent flurry of retirement announcements that NRCC Chairman Tom Cole of Oklahoma might need a full-time assistant just to put out statements praising departing members as great public servants and expressing confidence that the Republicans will be able to hold on to their newly “open” seats.

Within a period of five working days beginning Thursday of last week, three House Republicans — New York’s James T. Walsh , Florida’s Dave Weldon , and Virginia’s Thomas M. Davis III — all announced their intentions to leave at the end of the current 110th Congress.

Granted, health problems and/or age have been factors in some Republicans’ departure plans. And who am I to doubt the sincerity of a member who says he or she is quitting to spend more time with the family? It’s just that, for many members at least, the idea of leaving behind that hard-won congressional career seems a much more attractive option when one’s party is stuck in the minority doldrums than when it is ascendant and the prospects of committee chairmanships and other legislative perks loom.

The retirement surge becomes a double-edged problem for congressional Republican strategists who are hoping to make the best of the 2008 campaign. It creates a gloomy environment, as it appears that even many Republican incumbents view a quick return to the majority as highly unlikely. But in a more practical sense, it makes a Republican comeback much more difficult by increasing the party’s vulnerability in many of the states and districts left open by the departees.

On the Senate side, one Republican seat, in Virginia, is strongly favored to be won by the front-running Democrat, former Gov. Mark Warner. Four other contests for Republican seats, in Colorado, Minnesota, New Hampshire and New Mexico, are rated by CQ Politics as “No Clear Favorite” tossups.. And three of those five seats have been left open by retiring Republican members: John W. Warner of Virginia, Wayne Allard of Colorado and Pete V. Domenici of New Mexico. While Allard probably would have faced a tough race had he run again this year, popular veterans Warner and Domenici would have been strongly favored had they sought re-election.

The difference between a House incumbent running and retiring was accentuated when Virginia’s Davis announced Wednesday that he would not run for an eighth term. Recent Democratic gains have made Davis’ 11th District in the Northern Virginia suburbs of Washington, D.C., highly competitive. The long-standing popularity of Davis, a political pragmatist, made him a solid bet to hold the seat had he run. With Davis stepping aside, CQ Politics changed its rating on the race all the way from Safe Republican to No Clear Favorite.

With Democrats staging serious challenges to take over several other open Republican seats — and going after a number of incumbents, some of whom won close races in 2006 — the GOP will have to focus heavily on playing defense, at a time when funds for their Senate and House campaign committees are running low. This will leave the Republicans with very limited resources to finance challenges to take back at least a share of the 30 House seats they lost to the Democrats in 2006. The Democrats, by contrast, are much more flush with cash, and thus can fully finance more of their top-tier challengers, and invest some “venture capital” in more than a handful of longshot bids.

All this prognostication comes with the caveat that a lot can change in politics over the course of nine months, and we swear that’s not just a cover-your-butt disclaimer. While it was evident by the end of January 2006 that the then-minority Democrats had a chance to make gains, it was hardly obvious that the swing would be as big as it turned out to be, or that virtually all the breaks would go that party’s way. Should the situation in Iraq or the outlook for the economy suddenly turn bright — and if the public were apt to credit the Republicans for those developments — we could be looking at a whole different picture come November.

Based on what we see today, though, it looks like a strong Democratic year again in congressional politics, with Republicans’ hopes for preventing a Democratic-dominated Washington dependent on the race for the White House.