Turning heads in Des Moines, Rep. Ron Paul of Texas campaigns for the White House. (Jim Lo Scalzo for USN&WR)

Mitt Romney won the lion's share of presidential delegates in Tuesday's Republican primaries, but insurgent Ron Paul and his highly motivated supporters are still determined to push their libertarian agenda at the Republican National Convention in Tampa this August. They could also deny Romney a show of party unity as he tries to rally the GOP for the general election campaign against President Obama.

Paul, the only GOP challenger left against Romney, is focusing on state conventions where his supporters' superior organizing ability and never-say-die attitude have resulted in important delegate gains recently in Maine, Nevada and Alaska.

Paul, a U.S. representative from Texas, argues that his strength lies not only with Republicans. "This philosophy of freedom and individual liberty and limited government is appealing to independents and moderates and even progressive Democrats, when it comes to civil liberties and foreign policy," Paul told CNBC Tuesday. "So there's nothing automatic about my appeal only being to Republicans."

Paul said he's not ready to endorse Romney. "I'm not thinking about that as much as what kind of presence we'll have, how many people we're going to have there, and what kind of an influence we can have on the platform in Tampa," he noted.

Asked if he would run as an Independent this year, he repeated what he has said before: "I don't have any plans for that."

Paul strategists won't tip their hand, arguing that they want to take Romney supporters and old-guard party leaders by surprise. But Missouri's state convention, starting on May 18, is apparently high on their target list. Also considered priorities are Idaho, Iowa, Louisiana, Minnesota and the state of Washington.

Washington could be particularly fertile ground for Paul. The state's GOP convention will be held May 30 to June 2, when delegates will be chosen to the Republican convention. State party leaders think Paul's forces have the wherewithal to scoop up more delegates than expected, perhaps even a majority. "In a caucus convention system, they are formidable," Chris Vance, former chairman of the state GOP told the Associated Press. "They are motivated. They will come early and stay late."

Paul's supporters have already demonstrated an ability and an eagerness to use often-arcane party rules to battle for every delegate slot.