If the Democrats’ worst-case scenario comes true on Nov. 2, according to top election prognosticators, they won’t just lose the majority in both chambers of Congress, but in the House, the GOP could potentially end up with a 15-seat majority.

Republicans in the House need to net 39 seats to win control. Race predictor Stu Rothenberg of the Rothenberg Political Report says the GOP gaining 55 seats is “quite possible,” Dr. Larry Sabato of the University of Virginia says Republicans could pick up as many as 47 seats and the Cook Political Report says the GOP will win at least 35 seats.

“The worst case Election Day scenario for Democrats is losing both the House and Senate to the GOP,” says Isaac Wood, an editor for Sabato’s Crystal Ball. “Just a few months ago neither of these seemed poised to change hands and even now many are wondering if the Senate is really in play. The economic news keeps getting worse for Democrats and if it continues on that path, we could be moving towards that worst-case scenario.”

As for the Senate, Sabato acknowledged last week for the first time that Republicans have a shot — even though the chances are not good — at winning a majority in the upper chamber by picking up the 10 seats needed to win control. Charlie Cook of the Cook Political Report also wrote that “the possibility of a GOP takeover is growing,” arguing the GOP has six seats in the bag with chances to win in states like Colorado, California, Wisconsin, Washington and Nevada.

While these election analysts doubt the GOP can pull it off, in a worst-case scenario, the Republicans could win the Senate plus two seats to spare. “The absolute highest they could go is a 12-seat gain,” Wood said, while stipulating that it was a “very unlikely scenario.”

These positive prognostications for the GOP come on the heels of other positive news for the Party: In the history of Gallup polling, Republicans have never held as wide a margin over Democrats as they do now, according to the results of last week’s generic poll of party preferences of registered voters. An ABC News/Washington Post poll this week shows Republicans leading Democrats by 13 percent, the widest GOP margin since 1981 for the poll.

“The key for Obama and Democrats is to prevent that worst-case scenario, holding the Senate and tamping down on the GOP’s all-but-imminent House majority,” Wood said.

“They need to cross their fingers and hope for some economic progress, while spending their substantial cache of campaign money on as many TV ads as possible between now and November,” he continued. “If they can outspend the GOP, they may hold some seats that otherwise would have flipped.”

While the Democrats’ worst case scenario is losing control of both houses of Congress, for Republicans, it’s missing the chance to win a majority because the energy of the Tea Party movement didn’t help them win seats, but actually cost them some.
Democrats are hoping the often-times more conservative, Tea Party-backed candidates who won GOP primaries scare off enough voters to prevent Republicans from winning seats they should be able to pick-up or retain in states like Nevada, Florida or Kentucky.

“When we talk about what kind of an impact the Tea Party is going to have on the midterms, what I’m watching are these seats where the Tea Party has nominated candidates over more viable Republican candidates,” Jennifer Duffy of the Cook Political Report told The New York Times recently. “That’s my measuring stick.”

Before this summer, for example, it appeared that Republicans had the open Florida U.S. Senate seat locked up in their column. But after candidate Marco Rubio consolidated the conservative, Tea Party support, his primary opponent, Gov. Charlie Crist, left the GOP to run as an independent, dramatically increasing the chances that either a Democrat or an independent candidate could be elected.

In Nevada, Republican Sharron Angle — ardently supported by many in the Tea Party movement — is running neck-to-neck with Senate Majority Leader Harry Reid. It’s widely believed that the very-unpopular Reid would be trailing any of the other top Republican challengers eliminated in the GOP primary.

National Democrats have made it an integral part of their November strategy to vilify the so-called Tea Party-backed Republicans and marginalize them as outside the mainstream. If that strategy works — and keeps competitive seats from going to the GOP — the Tea Party could be blamed.

“It could be the difference between getting the majority or not,” Duffy said.