For Kentucky Sen. Rand Paul, his Wednesday night speech at the Republican National Convention is not just a prominent speaking slot. It represents a symbolic passing of the torch from father to son, and an opportunity to forge a deeper connection with the mainstream of the party than Ron Paul ever did.

Paul is his father’s son. He has carried on the fight for auditing the Federal Reserve, which is now part of the Republican platform. He has extended that call to auditing the Pentagon, one part of the government that is sacrosanct to many Republicans. Senator Paul has opposed foreign wars in Iraq and Libya, while demanding any conflict be authorized by a congressional declaration.

But the younger Paul has also emerged as a leader in the broader tea party. His 2010 Kentucky primary victory over a candidate handpicked by Senate Republican leader Mitch McConnell was one of that movement’s biggest triumphs over the GOP establishment. Unlike his father, Rand Paul adjusts his stump speech for different audiences and is comfortable delivering conservative red meat.

Paul may have previewed his line of attack against President Barack Obama in the GOP weekly address Saturday. “As the president campaigns against those who succeeded, as the president vilifies those who employ millions of workers, he condemns the very system that made America great,” Paul said. “Today there is a war going on for the heart and soul of America, a war between those who believe in the American dream and those who cannot grasp what makes America great.”

“There’s a battle going on between those who would respect the Constitution and those who would scrap it for the South African constitution,” Paul continued. He described the president as “missing in action” and denounced those who “would bow down and apologize for capitalism and profit and America’s exceptional history.”

Not only is Paul a successor to his father, but he has an opportunity to fill a void within the Republican Party. None of the candidates who tried to block Mitt Romney’s nomination from the right — Rick Santorum, Newt Gingrich, Rick Perry, Michele Bachmann or even Herman Cain — were perfect fits for the tea party mood. They were episodic advocates of government-cutting and few of them seemed animated by fiscal issues.

Paul speaks in stark terms about the country’s looming fiscal crisis, declaring even Paul Ryan’s budget plan inadequate for the challenge. But his views on civil liberties and foreign policy give him the potential to reach out to independents. While his father was more of a loner, Senator Paul has tried to be a bridge-builder, forming unlikely alliances with legislators as diverse as Oregon Democratic Sen. Jeff Merkley and South Carolina GOP Sen. Lindsey Graham.

But Paul’s task won’t be easy. Some of his father’s most ardent supporters don’t like the compromises his son has made with the Republican Party. Justin Raimondo, a longtime paleolibertarian writer with some influence among rank-and-file Paulites, blasted Rand’s endorsement of Romney as a betrayal.

In a column titled “Rand Paul’s Oedipal Drama,” Raimondo wrote, “While the establishment Republican leadership is using every dirty trick in the book – and a few new ones – to stop Ron Paul’s duly-elected delegates from being seated, their candidate’s son is going over to the enemy!”

On social networking sites where Ron Paul supporters congregate, the Romney endorsement drew an angry response. From all-caps rants to simple assertions like “Rand Paul, you disgust me,” evidence mounted that Ron Paul’s support won’t be 100 percent transferable to his son.

The libertarian website LewRockwell.com, edited by a former Ron Paul congressional aide, became a clearinghouse of news about the 2008 and 2012 Paul presidential campaigns. Mentions of Rand Paul are few.

The Ron Paul movement is a potential source of fundraising and activist muscle for a future Rand Paul campaign. But the senator will have to move far beyond his father’s base to become a bigger figure in the party or a realistic threat to win its presidential nomination. That’s where his second challenge comes in.

While some Ron Paul supporters don’t think he is enough like his father, other Republicans worry he is too much like him. Two years ago David Frum called Paul’s senatorial nomination “a depressing event for those who support strong national defense and rational conservative politics.” Frum asked, “How is it that the GOP has lost its antibodies against a candidate like Rand Paul?”

Paul’s critics in the party have mostly kept their powder dry. There have been battles over the National Defense Authorization Act, the Patriot Act, and Libya (all of which Paul opposed) and occasionally testy exchanges on the Senate floor with Senator Graham or Arizona Republican Sen. John McCain. But with domestic policy dominating and Paul still a popular figure among conservatives, there has been no effort to read him out of the party in the style of Frum’s 2003 “Unpatriotic Conservatives” essay for National Review.

But Paul has shown he can mediate between his father’s supporters and the rest of the Republican Party before. In 2011, Paul was scheduled to speak at the Conservative Political Action Conference. He was preceded by former Defense Secretary Donald Rumsfeld, who receiving CPAC’s “Defender of the Constitution” award, and former Vice President Dick Cheney, who took part in the presentation.

Cheney and Rumsfeld were two architects of the Iraq war. The room was filled with young Ron Paul supporters waiting to hear from the man who would take over the family political business. The crowd jeered loudly. As Slate’s David Weigel asked, “Whose bright idea was it to put Rumsfeld and Cheney in front of screaming libertarians?”

The scene was ugly. Cheney and Rumsfeld certainly did not get the reception CPAC organizers had planned. When Rand Paul walked out, facing a room mixed with Rumsfeld admirers and his father’s fans. He proceeded to deliver a speech that was well received by attendees on both sides, emphasizing common ground.

Paul was similarly deft in his remarks to his father’s valedictory rally in Tampa. If he can repeat that feat at the main event, convention organizers will be pleased — and his political career may enter a new phase.

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