SALEM, Ore. -- Businessman Mike Erickson has loaned another quarter of a million dollars to his congressional campaign and launched a new round of TV ads attacking Republican rival Kevin Mannix's past support for tax hikes as a legislator.

Erickson's loan of $250,000 brings to $590,000 the amount of his own money he's chipped in for this year's bid for Congress. He spent $1.6 million of his own money on his unsuccessful 2006 race against Democratic Rep. Darlene Hooley, who's not seeking re-election this year.

Erickson's latest loan triggers the "Millionaire's Amendment" under federal campaign finance law that allows candidates running against wealthy opponents to receive larger contributions from individuals. It will triple the amount of money Mannix can collect from individual contributors, to a total of $6,900 from each individual donor.

Much of Erickson's money has gone into blanketing the airwaves with TV ads aimed at overcoming Mannix's better name recognition among 5th District Republican voters who will choose a nominee in the May 20 primary election.

The 5th District is considered one of the most wide-open congressional races in the country, and both national parties have indicated they would pour big money into winning the House seat in the fall election.

Erickson's latest TV ad, which began airing this week, takes aim at the various tax increase plans Mannix supported during his time in the Legislature.

Mannix began his 10-year career in the Legislature as a Democrat and largely voted with his party on fiscal issues, even writing bills to raise alcohol taxes to fund treatment programs and hike gas taxes for road building.

"We have found at least 83 times that Kevin has voted as a legislator to raise taxes," Erickson campaign spokesman Cary Evans said.

Mannix's campaign spokeswoman, Amy Langdon, said some of those involved referring tax measures to voters. In more recent times, especially in the years after Mannix switched his party affiliation to Republican and served as state GOP chairman, he took a leadership role against tax increases, she said.

"Back when he was state party chairman, he led the fight against Measures 28 and 30, the two largest tax increases in Oregon's history," that were defeated by Oregon voters in 2003 and 2004, Langdon said.

As for the nearly $600,000 that Erickson has loaned to his campaign, Mannix this week accused the Lake Oswego businessman of trying to "buy this seat in Congress."

"I think the voters should let him know that this seat is not for sale to the highest bidder," Mannix said in an interview.

Evans, Erickson's spokesman, countered by saying that the loans are a "secondary issue" and that Erickson has raised more money from individual contributors than Mannix has to date -- about $300,000 compared with Mannix's $180,000. Erickson has been raising money since last year and Mannix began his campaign in March.