Is the Senate becoming riper for a Republican takeover?

Surging challenges to two Democratic incumbents – Patty Murray in Washington and Russ Feingold in Wisconsin – are a reason that chances for Republican takeover of the US Senate may be rising in Election 2010.

The conventional wisdom on the midterm elections has been that the House is vulnerable to a Republican takeover, but the Senate? Not so much.

It’s still true that the Republicans have an easier path to a House takeover, with so many Democratic-held seats in play. But with strong challenges emerging against two Senate Democratic incumbents previously seen as safe – Patty Murray of Washington and Russ Feingold of Wisconsin – and the national atmospherics heavily favoring the Republicans, Democrats increasingly have their work cut out for them to save control even of the Senate.

Add to that the possibility that one or even two senators currently in the Democratic column could flip to the Republican side if the GOP gets close to a takeover on Nov. 2. Let’s say the Republicans make a net gain of nine seats – one short of the 10 they need for a majority. Speculation will then immediately turn to Sen. Ben Nelson of Nebraska, a conservative Democrat from a red state who sometimes sides with the Republicans. Less likely but still conceivable as a party-switcher is Sen. Joe Lieberman of Connecticut, an independent who caucuses with the Democrats but is seen by some Democrats as not completely with the team.

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If the Republicans get close to a majority and offer one or both of these senators a committee chairmanship, that could sweeten the deal.

“So you’ve got two on the Democratic side you’ve got to worry about,” says Peter Fenn, a Democratic communications strategist.

Senator Lieberman already chairs a committee for the Democrats – Homeland Security and Governmental Affairs – but in politics, there are no guarantees. The Democrats still have to wonder if they might lose him under certain circumstances.

What’s more, it’s looking increasingly possible, though still not likely, that the Republicans could take over the Senate without the help of party-switchers. In the event of a tsunami-size wave of voter discontent, the Democrats’ large majorities in both houses – 59 to 41 in the Senate, 256 to 178 (and one vacancy) in the House – could easily be swept away. Typically, Senate races are not as vulnerable to the national mood as House races, but in this cycle, Republicans believe they could be.

A survey by Republican pollster Glen Bolger released Tuesday shows that in 13 states with competitive Senate races, the Republican candidates are leading on average by a margin of 47 to 39 percent. Candidates’ names were used in the poll (except in the few states with primaries pending), so it was not a generic test. In the eight seats currently held by Democrats – Arkansas, Colorado, Delaware, Illinois, Indiana, Nevada, Pennsylvania, and Washington –the Republican leads by an average of seven percentage points. In the five Republican seats – Florida, Kentucky, Missouri, New Hampshire, and Ohio – the GOP lead is eight points.

The poll was commissioned by American Crossroads, an outside Republican group that is fundraising to help GOP candidates.

“Senate races across the country appear to be drawn into the same national vortex that is impacting House races, as an earlier battleground survey that was conducted by Glen Bolger and others demonstrated fairly clearly back in June,” Steven Law, president of American Crossroads, said in a conference call Tuesday.

With 1,300 voters surveyed across 13 states, the sample size was not large enough for individual state results to hold credibility. But the larger trend in favor of Republicans taken as a whole is unmistakable. Independents are backing Republicans in these 13 states by a margin of 47 to 25 percent. And in a sign of a significant enthusiasm gap, “high-intensity voters” support Republicans by a 52-to-36 margin.

Still, there are almost three months to go before Election Day. The national mood is not likely to change, but developments could alter the dynamic in individual races. And Republicans are guarded about not raising expectations to unreasonably high levels, in which anything less than a full takeover of both houses of Congress is seen as a failure.

“A Senate takeover is just a possibility, it’s not a given,” said Mr. Law.

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