Outside spending in the 24th Congressional District is being followed by the Center for Responsive Politics.
The non-profit, nonpartisan think tank based in Washington, D.C., has been tracking spending on its website, OpenSecrets.org.
The latest data shows more than $1,600,805 has been spent so far on California's 24th Congressional race between Democrat Salud Carbajal and Republican Justin Fareed.
The race ranks sixth behind hotly contested districts in Kansas, Ohio, Nevada, Georgia and Maryland, but it ranks first among outside spending for the democratic candidate.
Democrats want to hold onto the seat being vacated by retiring Rep. Lois Capps.
With the help of Citizen Super PAC out of Austin, Texas, Republicans want to win back the seat.
Voter registration makes it appear to be a close race.
Some voters said they are concerned by big spending.
"I firmly believe big cats shouldn't buy the election," said Richard Anthony Baum.
Candidates are likely to spend big on campaign commercials and mailers.
One undecided voters said he is not easily persuaded.
"All the mailers just go into recycler for me and I don't watch the ads, " said Greg Reitz.
The League of Women Voters puts on forums to allow candidates to make up their minds by seeing the candidates talk about the issues.