The U.S. Senate race in Arizona has become a nearly $20 million affair - and there are still two more weeks until the election.

Outside spending on the race hit $10 million on Wednesday, with the money split about evenly between backers of Democrat Richard Carmona and Republican Jeff Flake.

In addition, the Carmona and Flake campaigns had combined to spend about $9.3 million through Sept. 30. Both will file new campaign finance reports this week that will show how much they raised and spent through Oct. 17.

On Nov. 6, voters will choose between Carmona, a former U.S. surgeon general, and Flake, a six-term U.S. congressman, to replace Sen. Jon Kyl, who is retiring after 18 years.

The latest big investment from outside groups came this week from the American Federation of State, County and Municipal Employees, which paid $1.2 million for a TV ad attacking Flake. The 30-second spot says Flake's "extreme right-wing ideas don't belong in Arizona."

Outside spenders include national party organizations, PACs and super PACs, and totals are updated daily on the Federal Election Commission website.

Groups supporting Carmona have spent $5.1 million, while organizations backing Flake have spent $4.9 million. The money has fueled a flurry of attack-style TV ads. One of the newest TV ads is from the National Republican Senatorial Committee, hammering Carmona by saying he's unable to work well with others.

Most of the money laid down by outside groups, $6.6 million, has been spent since Oct. 8. That's the week when early ballots went out.

Here are the six groups that have spent the most:

• National Republican Senatorial Committee (backing Flake) - $1.9 million.

• Democratic Senatorial Campaign Committee (backing Carmona) - $1.79 million.

• Club for Growth PAC (backing Flake) - $1.57 million.

• American Federation of State, County and Municipal Employees (backing Carmona) - $1.2 million.

• Majority PAC (backing Carmona) - $1.1 million.

• Freedomworks for America PAC (backing Flake) - $897,600.

Contact reporter Brady McCombs at 573-4213 or