Ro Khanna, left, and Rep. Mike Honda during their televised debate this month. John Green/Associated Press

An independent expenditure group is riding to Ro Khanna’s rescue with a radio spot pushing back against a TV attack ad that Rep. Mike Honda of San Jose is running against his fellow Democrat in the South Bay, which you can see here:

The pro-Khanna radio ad, which slams Honda’s TV spot and quotes a San Jose Mercury News fact-check story that called much of it “misleading or hypocritical,” is welcome news for Khanna. Honda’s ad is running regularly during prime time, and Khanna’s team has admitted it doesn’t have enough cash in the campaign treasury to counter it.

But in politics, as in much else, nothing comes for free, not even help from independent expenditure groups.

Khanna has refused to take any money from political action committees for his campaign, but he hasn’t denounced the help he’s received from the independent expenditure group, Californians for Innovation, even though it’s a super PAC formed strictly to collect more money than would otherwise be allowed in a congressional campaign and spend it to get Khanna elected.

And more than half the $480,000 taken in by Californians for Innovation so far comes from John Arnold, a former Enron energy trader and hedge fund manager who is slammed, though not by name, in Honda’s TV spot as a donor who “even helped cut off electricity to California.”

The charge comes from 2005 reports that Enron created artificial power shortages in California, helping to trigger the state’s energy crisis in 2000 and 2001 in an effort to raise the price of electricity.

Khanna and his backers complain that Honda’s charges are little more than an attempt to create “guilt by association,” airing night after night as many voters are deciding whom to support in a race that many see as a tossup.

Both candidates have upped the ante with new websites that feature nothing resembling a reasoned discussion of the facts.

Honda’s website, RightWingRo.com, has nothing more than a mail piece complaining that Khanna is trying to link himself with former GOP Rep. Tom Campbell, a moderate who once represented the South Bay district. Although Campbell has not endorsed either Democrat, the website notes that Khanna has the support of former Rep. Ernie Konnyu, a conservative Republican who was ousted by Campbell in 1988 after he was hit with charges of sexual harassment.

Khanna provides a little more entertainment with his “PAC-MIKE” game, which  uses images from the classic Pac-Man video game to pound home his charge that Honda has received much of his financial support over the years from special interests and political action committees.

But there’s good news for voters, tapped-out donors and probably both campaigns. With election day a week away, the end is finally near.