(NewsNation) — Key races in Arizona are getting a final push from former President Barack Obama, who is urging voters to support Democratic candidates Sen. Mark Kelly and Secretary of State Katie Hobbs.

The former president made a campaign stop in Phoenix on Wednesday night, hoping to help Democrats retain control of Congress.

The Senate race in Arizona is one of the races that could determine the balance of power in Congress.

Democrats still have the best chance of holding Kelly’s seat, though Republican Blake Masters has closed the gap in recent weeks.

Kelly, long considered one of the key Senate Democratic incumbents up for reelection, held a sizable lead over Masters for nearly two months after the GOP nominee emerged from an early August primary. Much of that was thanks to the onslaught of ads paid for by the Democrat’s fundraising juggernaut.

But the script has flipped in recent weeks, with Masters cutting Kelly’s lead to near the margin of error in most surveys.

The most recent Real Clear Politics poll has Kelly leading Masters by just 2.3 percentage points.

Democrats are now shifting their talking points from abortion to the importance of preserving democracy. This comes as several Republican candidates look to cast doubt on election integrity.

The latest NewsNation/Decision Desk HQ poll shows that nearly 80% of those surveyed say they have a “fair amount” or “great deal” of trust in the accuracy of the results of the upcoming midterm elections. Just 16% of respondents said they don’t have very much trust and 5% said they have “none at all.”

“The only way to preserve our democracy is if we together nurture and invest in it. That starts with electing people who know you, who see you, who care about you, who know what you’re going through,” Obama said.

While preserving democracy is seen as a vital issue for the Democrats, Arizona Republican candidates are pushing border security and law and order.

When it comes to the gubernatorial race, it is neck-and-neck, with Republican Kari Lake leading by roughly 2.8 percentage points over Hobbs.

NMW contributed to this report.