(Mamta Popat, Arizona Daily Star/AP Photo)

Former congresswoman Gabrielle Giffords spent the weekend campaigning for her ex-aide, Ron Barber, as he attempts to inherit the vacant seat left by his old boss in the House of Representatives.

On Tuesday voters in Arizona's 8th District will decide the outcome of the special election between Democrat Barber and Republican Jesse Kelly.

Giffords appeared with Barber today for a final push before the polls open. ABC affiliate KGUN in Tucson reports Giffords and husband Mark Kelly took the stage at a concert rally for Barber to a crowd of roughly 800 people.

Giffords has not had an active role in the campaign as she recovers from the January 2011 shooting at a "Congress on Your Corner" event at a Tucson supermarket. Six died that day after a gunman shot Giffords in the head before turning on the crowd. Barber was also wounded in the assassination attempt, being shot in the leg and cheek.

The three-term representative has had a difficult time speaking at length since the incident, and today her husband spoke on her behalf. Holding hands as they walked on stage, the former astronaut told supporters his wife's choice to resign and focus on her rehabilitation had been a "very difficult decision."

"You know she worked incredibly hard to first be elected to Congress and then to serve," he said. "It was her lifelong dream, but she knew that at that point it made sense for her to step down."

Kelly later said the special-election was about more than selecting the Grand Canyon State's next representative.

"This is a little about closure," he said. "This closure on Gabby's career in Congress, it wasn't when she resigned in January. I really truly believe that this is this coming Tuesday."

Giffords herself spoke briefly at the close of the concert, only offering words of gratitude.

"Thank you for your support. Thank you very much," she said.

The race between Barber and Jesse Kelly is considered hotly contested. The 8th District leans Republican by a margin of roughly 25,000 voters, making independents key for a Democratic victory. Giffords survived her own reelection battles through her history as a moderate Democrat. As an incumbent, Giffords faced off against Jesse Kelly in 2010 and succeeded with a margin of 2 percentage points.

Barber and Kelly's campaigns have remained largely civil, with most negative ads coming from outside groups. Republicans have sought to make their push a referendum of President Obama's national policies, rather than to personally target Barber or Giffords' local issues.