The special election primary to replace former Rep. Gabrielle Giffords (D) has been relatively quiet in recent weeks. But Tucson, Ariz., Republicans go to the polls today to pick their nominee, and the June 12 general election is about to explode on the political scene.

The de facto Democratic nominee is former Giffords staffer Ron Barber, and most Arizona Republicans agree their party will nominate veteran Jesse Kelly, who lost to Giffords in a memorably tough race in 2010.

At stake are the final months of Giffords’ term and the advantage a brief incumbency would provide the winner headed into the November election for a full term. Both parties have moved aggressively to claim the tossup seat, though it is unclear how much it will demonstrate a trend for future results.

“I think it is a referendum on President [Barack] Obama’s efforts to flip Arizona. This is a swing district,” Kelly spokesman John Ellinwood said. “To me, it is a bellwether.”

But even if Arizona becomes part of the contested electoral map for the presidential race, the unique circumstances of Giffords’ departure from office complicates the simple read of partisan politics. In January 2011, Giffords was among 18 people shot at a Tucson Safeway during a meeting she was having with constituents. Six people died, and although Giffords survived a bullet wound to the head, she resigned earlier this year to focus on her recovery.

Barber, who is assured of the Democratic party nomination to replace Giffords, was a member of her Congressional staff. He was injured on the day of the shooting. One party strategist said the effect of that day remains powerful in local circles.

“I just don’t see it becoming totally nationalized,” he said.

Republicans have called their primary “spirited” but say it has been positive. And although special elections can be unpredictable, party insiders assume Kelly will defeat a group of GOP challengers that includes former Air Force Col. Martha McSally and broadcaster Dave Sitton. The state Republican Party has already begun attacking Barber, confirming a report in the Arizona Daily Star that it had spent about $47,000 on direct mail and robocalls focused on Barber.

For his part, Barber has kept something of a low profile, making occasional television appearances.

“We haven’t heard a peep out of him,” one national GOP strategist said. “He’s going to try to get through the race with taking as few positions as possible. They know that the president is probably upside-down here.”

Barber has been solid in fundraising, with more than $500,000 reported in his preprimary special election report. And he did write an op-ed over the weekend about the importance of preserving Medicare, an issue that is likely to remain at the forefront with help from local and national Democrats, who see it as a winner.

If Kelly is the GOP nominee, Democrats plan to run a race similar to the one Giffords ran against him in 2010. The focus will be on Social Security, a sales tax, the minimum wage and Medicare.

For Kelly, the issues are similarly drawn from his national party’s playbook: the need to lower gas prices, raise domestic energy production, reduce federal regulation and lower taxes.

The complication in this otherwise straightforward Democrat-vs.-Republican race is the Giffords issue. There is a clear sense among Democrats that it’s important to hold what they call “Gabby’s seat.” And that will only be more intense if Kelly is the Republican candidate, given the hard-fought nature of his race against Giffords two years ago.

Barber has the backing of Giffords, her husband and her political confidants. A campaign insider would not indicate whether she would appear in commercials on Barber’s behalf.

There is also the fact that Arizona is a possible battleground state in the fall. The New York Times published a story Monday outlining the prominence of Arizona in Obama’s re-election plans, which would weigh heavily on this Congressional race in the fall, if not this summer.

The race to finish Giffords’ current term also will overlap a bit with the race to run for a full term in the fall. The deadline for filing to run in the fall is May 30, almost two weeks before the special election.

The district will become slightly more favorable to Democrats with the new map that will be used for the November contest. At least one Democrat, state Rep. Matt Heinz, has expressed interest in running in the fall, though he’s not on the ballot in the special election this summer. Also, some Republican candidates on the ballot in today’s primary have said they plan to run again when the new district is contested in the fall.