Republican U.S. Senate candidate Mike McGavick contributed another $500,000 to his election effort Friday, saying he and his wife "want to ensure that our campaign has the additional resources necessary to win this race."

In August, McGavick contributed $2 million of his money.

A former chief executive of Safeco, McGavick is worth between $36 million and $65 million, according to financial disclosure forms filed with the U.S. Senate.

McGavick's campaign said the latest infusion of personal cash does not trigger the Federal Election Commission's Millionaires Amendment, which allows opponents of self-financed candidates to raise additional money.

As of Oct. 1, McGavick listed contributions of $6.2 million.

His main opponent, Democratic Sen. Maria Cantwell, has brought in $16.4 million since 2001.

Six years ago, Cantwell, a former executive with RealNetworks, spent $10 million of her money to topple Republican Sen. Slade Gorton.

Polls, even those commissioned by the McGavick campaign, show McGavick trailing Cantwell.

McGavick's announcement Friday comes as the Republican Party funnels campaign cash to other Senate races around the country, but, so far, none to McGavick.

Brian Walton, a spokesman for the National Republican Senatorial Committee, declined to discuss the party's financial strategy, but he noted that volunteers were being sent to Washington state to work on McGavick's behalf.

McGavick's spokesman, Elliott Bundy, said the campaign never expected dollars from the national Republican groups because the party was dedicated to keeping its incumbents in office before diverting money to other races.

"It says nothing about their faith in our victory in this race," Bundy said. "We have the resources to win on our own."

Alex Fryer: 206-464-8124 or afryer@seattletimes.com