Democrat Kristen Carlson expanded her fundraising lead over Republican Ross Spano in the Congressional District 15 race during August and September, as one top analyst forecast the race razor close.

Carlson pulled in $579,017 for a total so far of $905,567, including $92,114 from herself, and showed $502,151 in cash.

Spano raised $191,530 for a total $439,952, including $104,500 from himself, and showed $165,613 in cash — but also debts of $165,366 to campaign vendors.

The Spano campaign responded with an analysis saying little of Carlson's money has come from within the district, and that much of it comes from New York and California through national, progressive fundraising organizations including Act Blue.

A recent poll done by a GOP-oriented firm and commissioned by the conservative Club for Growth, which is supporting Spano, showed Spano ahead by 7 points.

But after weighting that and other polls, polling analyst Nate Silver of FiveThirtyEight.com rates Spano ahead by less than 2 points and gives Carlson a 40 percent chance of winning in the GOP-leaning district.