After going dark for two days, California Senate candidate Tom Campbell (R) is back on the air.

As Ballot Box noted Wednesday, Campbell had pulled all his TV ads and was relying on Web ads and phone calls to get out the vote.

But the former congressman was back on the air Thursday with a new ad.

In it, he talks about how he has a better chance of beating Sen. Barbara Boxer (D-Calif.) than his rival for the GOP nod, former Hewlett-Packard CEO Carly Fiorina.

"I do have something neither of my opponents can offer. The Los Angeles Times announced a poll that shows me beating Sen. Barbara Boxer by 7 points. Carly Fiorina loses to Barbara Boxer by 6 points. Let's not lose this historic opportunity to replace Sen. Barbara Boxer," he said in the ad.

But that same poll also shows Campbell trailing Fiorina by 15 percent in the June 8th primary.

California is one of the most expensive media markets in the country and Fiorina put millions from her personal fortune into the race.

But, because Campbell is back on the air, his fundraising appeal must have paid off.

During the weekend, Campbell wrote on his blog about how he needed more financial support.

"The situation is clear: I can win if I have the resources to communicate in these final 9 days. If I don’t, we will not win – and Boxer will breathe a huge sigh of relief. Over the next 72 hours, I need to raise the resources to stay competitive against millions in attack ads; this election literally hinges on your response," he wrote.

Fiorina's campaign fired back at Campbell's new ad.

"He doesn't have millions to spend because he didn't raise enough money despite claims to the contrary. Two words describe this ad: desperate and sad," a campaign spokeswoman said.

-- This post was updated at 12:24 p.m.