What Kind of Democrat Will Arlen Specter Be? by Nate Silver @ 7:02 PM
My first take on Arlen Specter's defection to the Democratic Party was rather skeptical. Although the move is undoubtedly quite psychologically damaging for the GOP, there is room to question how much it will actually change the way that the sausage gets made in the Congress. If, for example, Arlen Specter is a Ben Nelson kind of Democrat, voting against initiatives like EFCA while driving an extremely hard bargain on health care, it is hard to see how Democrats gain, since there is little to distinguish a Ben Nelson type of Democrat from an Arlen Specter type of Republican.
I've now had the chance to examine the data on party-switching in more detail. When Congressmen have changed parties in the past, this has generally been accompanied by relatively material changes in their voting patterns -- thus, Democrats have ample reason to be pleased. Nevertheless, odds are that Specter will line up squarely in the conservative half of the Democratic caucus and will probably leave room to his left for a primary challenge.
Since 1980, according to Wikipedia, 20 Congressmen (16 Representatives and 4 Senators) have switched from one party to the other. The vast majority of these switches -- 17 of 20 -- were from the Democratic Party to the Republicans, mostly among conservative Southern Democrats in the 1980s and early 90s. Only Specter, Long Island Representative Michael Forbes and Jim Jeffords have gone the other way. I classify these Congressmen, by the way, by which party they caucused with regardless of how cute they tried to get about the label attached to their name. Thus Jeffords is treated as going from Republican to Democrat even though he still called himself an independent, whereas Joe Lieberman is not classified as a party-switcher because he never ceased caucusing with the Democrats.
I then looked up DW-NOMINATE data for each of these party switchers. DW-NOMINATE is a liberal-conservative classification which has conveniently assigned scores to each Congressman in each Congress from the 18th Century onward. DW-NOMINATE scores generally run from -1 for an extremely liberal Congressman to +1 for an extremely conservative one (although ratings slightly greater than 1 or less than -1 are possible under exceptional circumstances). The ratings for a select group of Senators in the 110th Congress follow below.
Click on the link to read the rest and see the graphs, since I didn't want to hotlink.
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Related to nothing, turning on the computer to see the news about Specter was a wonderful birthday present (I'm officially OLD!). :D