Voters will head to the polls Tuesday in southeastern Arizona to fill former congresswoman Gabrielle Giffords’s (D-Ariz.) seat just more than 17 months after she survived an assassination attempt.

Gabrielle Giffords, right, hasn’t been much of an issue in the special election for her old seat. Her former district director, Ron Barber, left, is the Democratic nominee in that race. (Matt York/Reuters)

Giffords’s Republican-leaning district looks to be neck and neck down the stretch, with neither side ready to predict victory. And both Democrats and Republicans agree that the shooting – in which Democratic nominee and former Giffords aide Ron Barber was also injured – has little to do with the ballots voters are casting.

“There is a group of people extremely dedicated to Gabby who will do anything for her,” said one Arizona Democratic strategist, granted anonymity to discuss a sensitive topic. “But I haven’t seen much evidence that the persuadable universe of folks Barber needs to win are going to be swayed by the shooting.”

Another Democratic strategist put it more bluntly: “Sympathy doesn’t win elections.”

Republicans pointed to the fact that Giffords hasn’t been a huge part of the campaign. Apart from an appearance with Barber set for Saturday and a Democratic super PAC running an ad highlighting GOP nominee Jesse Kelly’s 2010 comments critical of Giffords (which Barber notably distanced himself from Friday), she has hardly been front-and-center.

Indeed, Democrats are either declining to make Giffords an issue either out of principle – not wanting to exploit the tragedy – or because polling demonstrates that it simply doesn’t work. Or both.

The latter case wouldn’t be all that surprising. It’s not hard to think of other campaigns where the sympathy vote came up short.

In the 2010 Massachusetts special election, for example, Democrats tried early on to make the race about the legacy of former senator Ted Kennedy (D), who had died several months prior. But even with one of his signature initiatives in the balance – President Obama’s health care reform – Massachusetts voters elected a Republican, Scott Brown.

And there are other examples:

* In 2007, Georgians elected Rep. Paul Broun (R) after Rep. Charlie Norwood’s (R-Ga.) death, despite Norwood’s family endorsing another candidate.

* In 2000, Missouri Gov. Mel Carnahan (D) won election to the Senate posthumously three weeks after dying in a plane crash. But his wife Jean, who was appointed to the seat, lost a special election two years later. That race suggests a brief shelf life for the sympathy vote.

* By contrast, Sen. Paul Wellstone’s (D-Minn.) death in a plane crash on the eve of the 2002 election seemed to have little impact on ballots cast, with former Vice President Walter Mondale (D) losing to Republican Norm Coleman just 11 days later.

The totality of the evidence and the amount of time elapsed between the Giffords tragedy and Tuesday’s special election suggest the two events are very separate in voters’ minds. And we shouldn’t expect Tuesday’s election to hinge on what happened that tragic day at the Safeway in Tucson.

The Arizona special election is looking more and more like a pretty pure toss-up, and many will look to it for signs of momentum in this year’s election.

Here are 10 other races that are looking very competitive early in this cycle – the most toss-up-y of the toss-ups, so to speak. These races, depending on which way they go, should demonstrate which side has momentum over the next five months.

(Note: this list does not include seats that are likely to flip to the other party — only the seats where each side seems to have even odds of winning. It is in alphabetical order by state.)

To the line!

Arizona’s 1st district (Open seat): This open seat features a likely matchup between former congresswoman Ann Kirkpatrick (D) and former state senator Jonathan Paton (R). The district leans just slightly Republican, having gone for both President Bush and Sen. John McCain (R-Ariz.) in the 2008 presidential race by a narrow margin. But Paton has more to prove as a candidate after losing a 2010 primary to none other than Jesse Kelly, and Kirkpatrick got a big head start on fundraising.

California’s 26th district (Open seat): This Ventura County district was drawn in no-man’s land, with no incumbent living inside of it. It leans Democratic, but state Sen. Tony Strickland is a GOP fundraising star, and Democrats had to fight in last week’s primary to get state Assemblywoman Julia Brownley past an independent candidate and into the two-candidate general election. This district went 57 percent for Obama when the president walloped McCain in California, but also went for the GOP’s governor and Senate candidates in 2010.

Rep. Brian Bilbray (R-Calif.): Bilbray got a tough draw from the state’s citizen’s redistricting commission, and it showed in Tuesday’s primary. He took just 41 percent of the vote, while a pair of Democrats took 45 percent. It’s not yet official who his opponent will be, but former San Diego city councilman Scott Peters holds a lead as of now. Expect a tight race.

Rep. Mike Coffman (R-Colo.): Coffman’s 6th district moved about 7 percentage points more Democratic thanks to a court-drawn map in Colorado, and it’s now one of the swingiest districts in the country, having gone 54 percent for both Bush in 2004 and Obama in 2008. And Coffman’s comments in recent weeks about Obama not being “an American” at heart don’t help. The good news for the incumbent is that a former Democrat just entered the race as an independent, potentially splitting that party’s vote.

Rep. Judy Biggert (R-Ill.): Biggert faces former congressman Bill Foster (D) after Democrats targeted her under their new redistricting map. Biggert’s odds appear to be better than her Illinois GOP colleagues like Reps. Robert Dold and Joe Walsh, but the 74-year old will have to win a district that went 61 percent for Obama. That number is somewhat inflated because it was Obama’s home state, undoubtedly, but Foster is no slouch.

Rep. Bobby Schilling (R-Ill.): The freshman was targeted alongside Biggert and appears to have a fighting chance in a 60 percent Obama district. Schilling’s campaign recently released a poll showing him leading East Moline Alderwoman Cheri Bustos (D) 51 percent to 35 percent, even as Obama led in the district 51 percent to 41 percent over Mitt Romney. The race will get closer, but the poll is a good sign for Schilling.

Iowa’s 3rd district (Merged district): This redistricting cycle was strangely devoid of so-called “fair fight” districts, in which a Democratic incumbent is paired against a GOP incumbent in an evenly drawn district. In fact, this may be the only real “fair fight” this year. Rep. Tom Latham (R) has raised far more money, but Rep. Leonard Boswell (D) brings more of his old constituents into the merged district.

Rep. Mike McIntyre (D-N.C.): Like Illinois Republicans, North Carolina Democrats saw their districts decimated by the opposition party in redistricting. And just as Biggert and Schilling seem to be the most likely survivors in the Land of Lincoln, McIntyre is that guy in his state. But he’s got to win a district that went 58 percent for McCain and 62 percent for Bush, and Republicans got their top candidate through the primary in state Sen. David Rouzer.

Rep. Mark Critz (D-Pa.): Critz just won a tough member-versus-member primary with Rep. Jason Altmire (D-Pa.), but his work is hardly done. Now he’s got to win a district that went 54 percent Republican in each of the last two presidential races. The good news is that he comes from an area of the country that the GOP wave of 2010 hasn’t seemed to penetrate – Appalachia. He faces attorney Keith Rothfus (R).

Rep. Jim Matheson (D-Utah): Matheson, like McIntyre, is a longtime survivor in a conservative area. But Republicans are taking their last, best shot at him, and it just might work. Rather than trying to jam more Republicans into Matheson’s district, Republicans in the state legislature basically split it in thirds. Matheson chose to run in the 4th district rather than the district that was technically his – the 2nd – and his opponent is Sarasota Springs Mayor Mia Love, a young African-American politician that the GOP has high hopes for.