WASHINGTON — Bowing to political and economic reality, Republican presidential candidate Ron Paul said Monday that he will no longer actively campaign in the remaining primary states.

In an email to supporters, the 76-year-old Texas congressman said that to have "any hope of success" against presumptive GOP nominee Mitt Romney in the remaining megastates of Texas, California and New Jersey would require "many tens of millions of dollars we simply do not have."

But the libertarian House member said he would continue to battle for delegates in states holding upcoming statewide conventions and hoped to shape the GOP policy debate at the Republican National Convention and beyond.

"This campaign fought hard and won electoral success that the talking heads and pundits never thought possible," Paul told his backers. "But, this campaign is also about more than just the 2012 election. It has been part of a quest I began 40 years ago and that so many have joined."

Paul's announcement means he will not contest late-primary states such as his home state of Texas on May 29 and California and New Jersey a week later. But the candidate is pushing to maximize his delegate count in states where the delegate-selection process is under way — and supporters announced plans for another fundraising "money bomb" designed to finance their ongoing efforts.

"Our campaign will continue to work in the state convention process," Paul said. "We will continue to take leadership positions, win delegates, and carry a strong message to the Republican National Convention that liberty is the way of the future."

Despite his enthusiastic cadre of loyalists, Paul has accumulated only about 100 delegates from among the more than 2,200 who will descend on Tampa, Fla., in August for the Republican National Convention. And polls showed him trailing far behind Romney in Texas and California, the largest delegate prizes of the year.

richard.dunham@chron.com; samantha.wagner@chron.com