One year before Election Day 2008, Democrats appear poised to make significant gains in the Senate, according to new polls conducted exclusively for Roll Call.

Surveys done last week in seven states with competitive Senate races showed Democrats leading or tied in five, trailing narrowly in one, and with a significant deficit in the other. All seven Senate seats now are held by Republicans.

These polls, taken by SurveyUSA, an automated polling firm, found the approval ratings of Congress in the seven tested battleground states — Colorado, Maine, Minnesota, New Hampshire, New Mexico, Oregon and Virginia — abysmally low, and President Bush didn’t fare much better.

The four top Congressional leaders — Speaker Nancy Pelosi (D-Calif.), Senate Majority Leader Harry Reid (D-Nev.), Senate Minority Leader Mitch McConnell (R-Ky.) and House Minority Leader John Boehner (R-Ohio) — also had very low favorability ratings, though all but Pelosi were unfamiliar figures to many of the voters surveyed.

The war in Iraq continues to be the issue that voters most want Congress to address in the months ahead, though immigration and health care also scored highly in the Roll Call polls. Iraq and health care as campaign issues seem to benefit the Democrats, at least in the seven states surveyed. Immigration was a net plus for Republicans.

Each of the states has its own political dynamic (for summaries of Congressional races in all 50 states, please see the Roll Call Election Preview inside today’s edition), but an analysis of the poll data shows that many of the key trends currently are heading in the Democrats’ direction.

The brightest spots for Democrats among the Senate battlegrounds are in Virginia and New Hampshire, where their presumptive nominees had substantial leads.

In the likely general election race in Virginia between former Gov. Mark Warner (D) and his predecessor, ex-Gov. Jim Gilmore (R), Warner was preferred by 57 percent of those surveyed compared with 35 percent for Gilmore. In a hypothetical matchup with former Sen. George Allen (R-Va.) — who was defeated in his re-election bid last year and shows no interest in running for Senate in 2008, even as he plots an eventual political comeback — Warner led 52 percent to 42 percent.

Gilmore was regarded favorably by only 21 percent of the voters in the Roll Call poll, and unfavorably by 31 percent. Allen, whose re-election campaign was marred by controversy, was regarded favorably by 40 percent of voters and unfavorably by 34 percent. Warner’s favorable to unfavorable ratings were 49 percent to 26 percent.

In New Hampshire, former Gov. Jeanne Shaheen (D) held a 53 percent to 42 percent lead over the man who defeated her in the 2002 Granite State Senate race, Sen. John Sununu (R). In a trial heat with the other candidate seeking the Democratic Senate nomination, former astronaut Jay Buckey, Sununu led 49 percent to 36 percent.

In Colorado, where Sen. Wayne Allard (R) is retiring, Rep. Mark Udall (D) held a 48 percent to 41 percent lead over former Rep. Bob Schaffer (R) in the race to replace him. Significantly, in a state that leans Republican at the presidential level despite all the gains that Democrats have made there in the past two election cycles, Udall held a 5-3 edge among political independents.

In New Mexico, where the political situation remains fluid in the aftermath of Sen. Pete Domenici’s (R) retirement announcement, the leading Democrat in the race so far, Albuquerque Mayor Martin Chavez, held narrow leads over the two House Members seeking the GOP nomination, Reps. Steve Pearce and Heather Wilson. Both Pearce and Wilson led the other declared Democrat, real estate developer Don Wiviott.

But Rep. Tom Udall (D), who just two days after Domenici’s early October retirement announcement said he would not run for Senate, has disclosed in recent days that he is reconsidering that decision. He was not tested in Roll Call’s poll — and his plans were disclosed too late to be included in the Election Preview, which went to press on Thursday. Lt. Gov. Diane Denish (D) on Friday announced that she would not become a candidate for Senate.

New Mexico Gov. Bill Richardson (D) remains an overwhelming favorite in the Senate race, according to the Roll Call poll. But Richardson continues to insist that he has no interest running for the post and is concentrating on his White House bid.

In Minnesota, the two leading Democrats vying to challenge Sen. Norm Coleman (R) ran essentially even with the first-term lawmaker. Coleman led entertainer Al Franken (D) 46 percent to 45 percent — well within the poll’s 3.8-point margin of error — and he was tied with trial attorney Mike Ciresi (D) at 44 percent apiece.

Franken, the forked-tongue comedian, author and former talk-radio host, had high negative ratings, which could hurt him if he becomes the Democratic nominee. He was viewed unfavorably by 37 percent of those surveyed, compared with a favorable rating of 22 percent. Ciresi may have more potential against Coleman, simply because he is less well-known: The wealthy trial lawyer had a 12 percent favorable rating and an 18 percent unfavorable rating. But 43 percent of those polled said they were unfamiliar with him (18 percent were unfamiliar with Franken).

The news was better for Republican incumbents in Oregon and Maine.

In Oregon, Sen. Gordon Smith (R) led the favorite of the Democratic establishment, state Speaker Jeff Merkley (D), 48 percent to 39 percent. Curiously, the insurgent Democratic candidate, attorney Steve Novick, finished just 6 points behind Smith.

In Maine, Sen. Susan Collins (R) held a commanding lead over Rep. Tom Allen (D), 55 percent to 38 percent. Collins led in every age group and pulled 51 percent of independent voters and fully one-quarter of all Democrats surveyed.

The Democrats’ best strategy to beat the moderate Senator will be to tar her as a clone of Bush. Of the seven states in Roll Call’s survey, Maine is where Bush fared the worst: 28 percent approved of his job performance and 65 percent disapproved.