Would Scott Murphy, who incidentally now trails Jim Tedisco by 12 (!) votes, have "buried" him by 6-10 points if the two candidates went head to head on November 4th? This is Rothenberg's assertion. Unfortunately, he does not provide any evidence to support his conclusion, nor is at all intuitively obvious.
[T]hink what this election would have been like for Republicans if it had occurred last November. Murphy would have buried Tedisco by 6, 8 or maybe 10 points.
The absence of George W. Bush as a factor in this race helped Tedisco, and it suggests that while Republicans certainly haven’t turned the page on the past eight years and still have plenty of damage to repair, they have hit the bottom and are starting to bounce back. That is good news for the GOP.
There are three benchmarks that one can conceivably use to infer what Scott Murphy's performance might have been on November 4th.
Option one is to compare it against the Democrat who was actually running that day -- incumbent Kirsten Gillibrand. Gillibrand won her race decisively on November 4th, securing 61.8 percent of the vote against opponent Sandy Treadwell. However, Gillibrand was an incumbent, and for a number of reasons ranging from fundraising muscle to deterring stronger challengers from entering the race, the incumbency advantage is quite powerful in Congressional elections. Even in 1994, a very bad year for incumbent Congressmen, about 90 percent of them were re-elected. So it would be hard to consider this an apples-to-apples comparison. And by the way, if either candidate had incumbent-like advantages in NY-20 on Tuesday, it was not Murphy but Tedisco, who started out with much stronger name recognition as the Minority Leader of the New York State Senate; Murphy had never run for elected office before.
Option two is to compare Murphy's performance against Barack Obama's on November 4th, as Michael Barone does. I don't think there's anything terribly wrong with doing this, although it's a little imprecise; if memory serves, there were something like 50 Congressional Districts in which a Republican won the Congressional Seat while Barack Obama won the Presidential ballot, or vice versa. In any event, Murphy comes out looking reasonably good if you do this; he won 50 percent of the vote on Tuesday (give or take some small fraction) versus Obama's 51 percent on Election Day.
The third method, which I consider to be the most robust, would be to compare the results in NY-20 to that of similar congressional districts. I already did a version of this based on the Cook PVI, and found that a 50:50 split of the vote is almost exactly what you'd expect in this district. Among 58 districts with PVI's of between R+1 and R+4 (NY-20's is either R+2 or R+3, depending on which elections you include in the total), Democrats won 30 seats (including NY-20) on November 4th and Republicans won 28.
A slight variant of this approach would be to look 2008 data only. Barack Obama won 51 percent of the vote in NY-20 on November 4th. How did congressional candidates perform in other districts where he received between, say, 50 and 52 percent of the vote? Again, we see essentially an even split; Republicans won 16 of 30 such districts and Democrats won 14:
Won by Republicans (16): CA-24, CA-25, CA-26, CA-44, CA-45, CA-50, FL-10, FL-18, MI-4, MN-3, NE-2, NJ-7, NY-23, VA-4, WI-1, WI-6
Won by Democrats (14): FL-22, KS-3, MI-1, MI-7, MN-1, NC-2, NJ-3, NY-1, NY-19, NY-20*, NY-24, TX-23, VA-2, WA-3
There may well be a case to be made that Scott Murphy would have won by 6 or more points on Election Day. But the case doesn't make itself, nor does Rothenberg really try to make it. As Markos Moulitsas points out, in fact, Rothenberg had written back in February that he thought NY-20 would be a tough hold for the Democrats!
The more interesting and credible argument, I think, is advanced by Barone:
The more appropriate benchmark is the 2008 presidential election, in which Barack Obama carried the district 51-48 percent. Comparing that to Murphy's current 50.01-49.99 percent lead, we find Murphy running .7 percent behind Obama and Tedisco running 2.3 percent ahead of McCain. We don't see the falloff here from the Obama percentage that we did in the December 2 Georgia Senate runoff, in which Democrat Jim Martin won 43 percent of the vote in a state where Obama won 47 percent of the vote. In that election, in the two special elections for the House in Louisiana in December and for a set of legislative and Fairfax County special elections in Northern Virginia in January and February, Democratic turnout dropped off much more sharply than Republican turnout as compared to the November 2008 results. That's not the case here. Tedisco got 49 percent of the McCain vote; Murphy got 46 percent of the Obama vote—a difference, but not a big one. Obamaenthusiasm is reasonably alive and well in Upstate New York.Barone's argument is that we might indeed expect Democratic performance to decline from November 4th in certain types of congressional districts -- in particular, those districts with large numbers of younger and/or African-American voters, who have historically been inclined to turn out in much greater numbers when there is a Presidential race on the ballot (and were particularly so for Barack Obama) than when there isn't. However, NY-20's constituents are very white and relatively old, so we didn't see much drop-off there.
Or at least in a district in which there are relatively few of the two voting blocs that gave Obama huge majorities. The district's population is only 2 percent black. And although there are many small colleges in the district, there aren't the huge campuses or large university towns or thriving singles neighborhoods that you find in some districts. Black turnout seems to have declined sharply in the special elections mentioned above. There simply wasn't much black turnout to decline in the New York 20th.
I find this case rather persuasive; in fact, it dovetails pretty well with what I recently wrote at Esquire about midterm elections:
The answer to the riddle may be this: While a president’s coattails can be strong at the midterms, they are not as strong as when the president himself is on the ballot. And in fact, the bigger a president’s coattails are when he is elected, the more trouble his party tends to have two years later. Therefore LBJ, who had cruised to election by 23 points in 1964, saw his party shed nearly fifty seats two years later. But George W. Bush, who had in fact lost the popular vote in 2000, was one of the few incumbents to see his party gain ground in the subsequent election.That is, we should expect some decline for Congressmen who come from the same party as the incumbent President, because some of their votes came as a result of Presidential coattails -- coattails they won't have when the President isn't on the ballot. In fact, the larger the sitting President's victory margin upon his last election to the Oval Office, the steeper this decline tends to be.
Many of the voters who went to the polls in 2008 did so because of Barack Obama; almost 90 percent of those voters also happened to vote Democratic for Congress. But many of those voters will not turn out next year without a presidential race to pique their interest. Some of the same Democratic representatives who most benefited from Obama’s coattails in 2008, then, are also the most vulnerable to an upset. Their fate may depend on how much this president can personalize that election — and, of course, how much he can mobilize his powerful voter-turnout operation for them — and how well liked he can remain. Obama’s popularity is the Democrats’ greatest asset heading into the midterm elections in 2010 — but it is also in some sense their greatest liability.