Washington ? Republicans are planning to spend the vast majority of their sizable financial war chest over the final 60 days of the campaign attacking Democratic House and Senate candidates over personal issues and local controversies, GOP officials said.

The National Republican Congressional Committee, which this year dispatched a half-dozen operatives to comb through tax, court and other records looking for damaging information on Democratic candidates, plans to spend more than 90 percent of its $50 million-plus advertising budget on what officials described as negative ads.

The hope is that a vigorous effort to “define” opponents, in the parlance of GOP operatives, can help Republicans shift the midterm debate away from Iraq and limit losses this fall. The first round of attacks include an ad that labeled a Democratic candidate in Wisconsin “Dr. Millionaire” and noted that he has sued 80 patients.

“Opposition research is power,” said Rep. Thomas Reynolds, R-N.Y., the NRCC chairman.

The Republican National Committee has enlisted veteran party strategist Terry Nelson to run a campaign that will coordinate with Senate Republicans on ads that similarly will rely on the best of the worst researchers have dug up on Democrats. The first ad run by the new RNC effort hits Ohio Rep. Sherrod Brown, a Democrat, for voting against proposals designed to toughen border protection and deport illegal immigrants.

Because challengers tend to be little-known compared to incumbents, they are more vulnerable to having their public image framed by the opposition through attacks and unflattering personal revelations.

With polls showing the Republicans’ House and Senate majorities in jeopardy, party strategists said they have concluded that their best chance to prevent big Democratic gains is a television and direct-mail blitz over the next eight weeks aimed at raising enough questions about Democratic candidates that voters decide they are unacceptable alternatives.

“When you run in an adverse political environment, you try to localize and personalize the race as much as you can,” said Rep. Tom Cole, R-Okla.

In a memo released last week, Cole, who is running to succeed Reynolds at the NRCC, expanded on that strategy. The memo recommended that vulnerable incumbents spend $20,000 on a research “package” to find damaging material about challengers and urged that they “define your opponent immediately and unrelentingly.”

GOP officials said internal polling shows Republicans could limit losses to six to 10 House seats and two or three Senate seats if the strategy – combined with the party’s significant financial advantage and battled-tested turnout operation – proves successful. Democrats need to pick up 15 seats to win control of the House and six to regain power in the Senate.

Democrats’ hopes for the most part hinge on being able to nationalize the election and turn it into a referendum on the Iraq war, President Bush and the performance of the Republican Congress – all faring poorly in polls this year.

Bush will try to make terrorism the issue nationally, casting the election as a choice between two distinct approaches for protecting the nation from future attacks. Beyond that, however, most Republicans want to distance their elections from the national context.

That strategy is born of necessity. Republicans are alarmed by the large number of House and Senate incumbents who are trailing or tied in their internal polling. Many are attracting the support of less than 45 percent of likely voters. The political rule of thumb is that incumbents rarely win a majority of voters who make up their minds in the days shortly before Election Day.