WASHINGTON—Two political challengers in the Central Valley continued to rack up impressive fundraising totals in the first quarter of the year, showing that the region is likely to feature some of the state's most competitive congressional races in November.

Republican Ricky Gill, who is just 24 and not yet old enough to serve in Congress—though he would be by the next Congress—outraised Democratic Rep. Jerry McNerney in the quarter and has slightly more money in the bank than the incumbent. Gill raised nearly $317,000 while McNerney raised about $267,000. The two are running for the state's redrawn 9th Congressional District, a seat that is centered Stockton and stretches from the Sierra foothills to the San Joaquin Delta.

Democrats also have a challenger who is excelling on the fundraising front, former space shuttle astronaut Jose Hernandez. He raised about $313,000 in the first quarter but is still playing catch-up to the incumbent, Republican Rep. Jeff Denham. Denham raised less in the first quarter, $238,000, but also had a big head-start and now has nearly $969,000 in the bank.

California's congressional candidates had to report their fundraising totals for the first three months of the year by midnight Sunday. Over the past couple of decades, there have been few close congressional races in California, a result of political boundaries that were drawn to protect incumbents, but the fundraising totals point to several competitive races.

In 2008, voters approved the creation of the California Citizens Redistricting Commission to oversee the once-a-decade process. The new boundaries the commission created were drawn without regard to incumbency, and in a few instances incumbent lawmakers have been thrown into the same congressional district.

The most closely watched of those races features longtime Democratic Reps. Brad Sherman and Howard Berman in the 30th Congressional District. The San Fernando Valley race also promises to be among the most expensive in the state. Berman already has spent $1.7 million, while Sherman has spent nearly $1 million.

Berman has been winning the fundraising and endorsement battles in recent months. He raised nearly three times the amount of money that Sherman raised in the last quarter. Still, Sherman had such a head-start going into the election that he maintains a considerable cash-on-hand advantage. He has more than $4 million in the bank, while Berman's campaign has about $2.5 million.

Another Los Angeles County race also pits incumbent Democrats against each other, with freshman Rep. Janice Hahn taking on Rep. Laura Richardson in the Hispanic-majority 44th Congressional District. Hahn raised nearly $210,000, more than twice what Richardson raised. Richardson's campaign reported that it had less than $12,000 cash-on-hand at the end of the quarter, versus $175,000 for Hahn.

The totals for the quarter also show that a rematch between Democrat Ami Bera and Republican Rep. Dan Lungren in the redrawn 7th Congressional District should be close. Lungren was able to cut into Bera's fundraising edge by collecting more than $500,000 in donations. Still, it's unusual for a challenger to have raised more money than the incumbent at this stage of the race. Bera has about $1.1 million in the bank versus nearly $900,000 for Lungren.