WASHINGTON - Senator John McCain has retreated from his longtime commitment to public financing of campaigns since he started planning his 2008 bid for the presidency, according to nonpartisan advocates who had hoped McCain would be a strong voice for reform during the most expensive presidential campaign in history...

McCain's campaign said the presumptive Republican nominee, who completed a fund-raising swing through western states Friday, has "a clear and long record" of supporting campaign finance reform, and has not recently advocated an expansion of public financing because it would be inappropriate for him to take a lead role in increasing funding for a program from which he could benefit.

But campaign finance reform advocates say they are distressed at what they see as McCain's abandonment of the issue at a time when supporters of reform most need bipartisan backing of efforts to control the influence of money in campaigns.

"Clearly, McCain has worked hard for a number of reforms, most notably BCRA" - the Bipartisan Campaign Reform Act that bans big-money donations by labor unions, corporations, and wealthy individuals, said Arn Pearson, vice president for programs at Common Cause, an advocacy group. But "since he's decided to be a presidential candidate, he has backed off on taking public positions on those issues," imperiling reform efforts on Capitol Hill, Pearson said.