MEMPHIS, Tenn. - Lunging for control of the GOP ahead of high-stakes elections, the Republican National Committee on Friday took steps to end free-for-all presidential debates and vowed to punish potential contenders who participate in rogue forums.

At the same time, an independent organization with deep ties to the conservative Koch brothers has elected to spend $125 million on the battle for control of the Senate this fall, giving the 168-member central party meeting a stark reminder that outside groups will have significant sway over Republican political fortunes through the 2016 presidential race.

One of those potential presidential contenders, Sen. Rand Paul of Kentucky, publicly broke with the GOP over voting rights, saying in an interview that officials should stop passing state laws that tighten controls on voting. The New York Times published the article Friday, the same day Paul spoke at a luncheon during the RNC meeting.

As he opened the party's meeting, RNC Chairman Reince Priebus said the national committee can't control everything in politics. "But we have an important mission," he said, "and we're going to get the job done."

As he spoke, reports circulated that Americans for Prosperity plans to escalate its television advertising across the nation, improve voter data collection and strengthen its 31-state ground operation. It was a bracing reality check for the RNC: Despite the committee's efforts, the GOP establishment won't be the only one setting Republican priorities.

A senior official with direct knowledge of Americans for Prosperity's plans confirmed the election blueprint, outlined in a memo distributed to Republican donors this spring. The official confirmed the memo's authenticity but wasn't authorized to publicly discuss its contents.

Industrialist billionaires Charles and David Koch have already funneled millions of dollars to conservative causes. Democrats including Senate Majority Leader Harry Reid have roundly criticized the billionaires and claim Republican policies are being dictated by an agenda to grow the Kochs' wealth.

In a nod to the Kochs' heft, the RNC passed a resolution condemning Reid for what it called "hyperbolic attacks ... on private citizens."

The struggle to mend a party split between populist and establishment factions has hung over the meeting in Memphis, with RNC officials looking for ways to make it harder for weak but vocal candidates to prolong nomination fights, roil debates and jeopardize the party's chances - again - of winning the Senate majority and the presidency.

The New York Times reported that Paul, the Kentucky Republican and darling of the anti-establishment segment of the GOP, said in an interview on the sidelines of the RNC meeting that the push on voting laws was alienating blacks.

Republicans have been strong advocates for such laws. In many cases the laws make casting a ballot more difficult for older voters and minority voters, who tend to support Democratic candidates.

"Everybody's gone completely crazy on this voter ID thing," Paul told the Times. "I think it's wrong for Republicans to go too crazy on this issue because it's offending people."

During his address to RNC members, Paul said Republicans should reconsider their policies about penalties for illegal drugs and anti-terrorism tactics. His remarks were politely received but unlikely to win him supporters among establishment-minded Republicans.

Paul's comments - and his loyal followers - were just the latest reminders that despite Republicans' efforts, taking greater control over the 2016 contest could prove difficult.

On Thursday, the RNC rules panel endorsed the creation of a 13-person committee that would limit how many presidential debates can take place and who can ask the questions. The full committee on Friday went along with that plan to ban candidates who participate in scofflaw debates from future RNC-backed sessions, by a 152-to-7 vote.

Several committee members said they were worried that activists might see their ability to prod candidates reduced under the new rule.

"You're going to squelch the ability of candidates to get to know their voter base, and the voter base to get to know their candidates," said Diana Orrock, a national committeewoman from Nevada. "As a voter ... I want to see the good, the bad and the ugly."

The RNC measure affects only debates as candidates vie for the GOP nomination; the bipartisan Commission on Presidential Debates will still have final say on the elections between the Republican and Democratic nominees during the general election campaign.

But the RNC recommendation did take a step at reining the haphazard debate style that characterized the 2012 selection progress. The freewheeling system provided a seemingly endless series of debates, from which former Massachusetts Gov. Mitt Romney emerged as the party's nominee, but only after weathering harsh criticism from his rivals.

"Spending too much time fighting with each other distracts the party from its ultimate goal, which is winning the presidency," said Bruce Ash, chairman of the RNC's rules committee. Others said the debate moderators during the 2012 were hostile to the GOP or were Democrats who wanted Obama to win a second term.

The RNC rule does not explicitly pick debate moderators.

Meanwhile, political operatives said Americans for Prosperity's $125 million investment does not include as much as $30 million more that the group's sister nonprofit organization expects to spend on voter education efforts, which are designed to support conservative causes but don't necessarily advocate for specific legislation or candidates.

The senior official with knowledge of the memo, first reported by Politico, said the group has already spent more than $20 million this year ahead of the November midterm elections.