By Stuart Rothenberg

Initial reports that Sen. Judd Gregg (R-N.H.) would be appointed Commerce secretary were invariably followed with a caveat that Gov. John Lynch (D) had agreed to appoint another Republican to fill the vacancy, thereby maintaining the current Senate balance of power and denying Senate Democrats a 60-vote majority.

The crucial question, however, is not whether New Hampshire's soon-to-be- appointed Senator is a Republican or will caucus with Republicans, but whether she will vote with Democrats to limit debate when other Republicans are trying to keep a filibuster going or pass a key amendment.

If Sen.-designee Bonnie Newman becomes the Democrats' 60th vote to bring the Employee Free Choice Act to the floor (assuming it ever gets that far) or to confirm a judge that other Republicans oppose, it won't matter what her party affiliation is.

In the early 1980s, then-Texas Rep. Phil Gramm still caucused with Democrats for months after he started voting like a Republican and working strategically with members of the GOP.

Some Republicans believe that Newman will vote pretty much as Gregg would have on fiscal matters, though they express less certainty about her vote on cultural matters and education issues.

But conservatives clearly have more than enough reason to worry because all of the praise being heaped on her by New Hampshire Democrats suggests she won't be as reliable as the least dependable of the GOP's current sitting Senators.

Newman, after all, endorsed Lynch when he first sought the governorship in 2002 against the sitting governor, Republican Craig Benson. And she has described herself as a "reasonable Republican" -- not exactly the kind of self-identification that suggests she has an altogether favorable impression of her own party.

Lynch's selection of Newman, who has already indicated she will not seek a full term, is a political masterstroke (as was President Barack Obama's selection of Gregg), even if the more liberal elements of his own party are unhappy that he picked a Republican.

In fact, the trade of Gregg for Newman is so one-sided in favor of Democrats that it is reminiscent of the 1964 deal in which the Chicago Cubs sent future Hall of Famer Lou Brock and two others to the St. Louis Cardinals for aging pitcher Ernie Broglio and others.

Democrats get rid of Gregg, who, had he sought re-election in 2010, would have been the GOP's strongest nominee, and get an open seat to shoot at instead. They get a new Republican Senator who has supported Democrats in the past, calls herself a moderate Republican and has the kind of r