Republican donors are setting up a multimillion-dollar war chest to help protect electable party candidates from primary challenges from "undisciplined" candidates from the fringe right.

The Conservative Victory Project, set up by the Karl Rove-backed Super Pac American Crossroads, seeks to become a bulwark against the kind of extreme views that have seen the party lose Senate seats in recent contests.

The people behind the idea said it is a push against indiscipline rather than any particular ideology. But it comes as the Republican party seeks to define itself after November's presidential defeat amid an apparent battle for the heart of the party.

It is also being framed by some as a push against the influence of the Tea party, the likes of which have seen the GOP dragged to the right in recent years.

Jonathan Collegio, spokesman for American Crossroads, said it was rooted more in the pragmatism William F Buckley rule, which has it that you should put forward the most conservative candidate that is capable of winning.

"I wouldn't classify this effort as being conservative versus moderate. It is about being the most conservative candidate that can win. If a candidate is undisciplined or unable to raise sufficient resources, it should be recognised," Collegio told the Guardian.

He added: "Our party has lost six Senate seats over the last two election cycles not because of our ideas but because of undisciplined candidates running weak campaigns."

The new push comes just months after the Republicans lost two high-profile Senate battles in which their candidate had expressed deeply conservative – and to most people's minds, offensive – views on social issues.

Then-Representative Todd Akin had been favourite to take a Senate seat representing Missouri before commenting on TV that pregnancy rarely occurs in the case of "legitimate rape".

Senior Republican figures called on him to step down from the campaign, but he refused to do so. The resulting backlash from, in particular, female voters saw him lose a seat that many party officials believed was very winnable.

Likewise, in Indiana, Republican candidate Richard Mourdock lost the Senate battle after suggesting that rape was "something God intended to happen".

Despite both men's comments being condemned by politicians from both parties, they continued to receive support from those towards the fringe of the party and continued to receive funding from right-wing groups.

It is such support that the Conservative Victory Project is seeking to counter. Collegio said that it would have "tens of millions of dollars" at its disposal to help established incumbents and favoured candidates fight in primary battles.

Such Republican v Republican battles could be a feature of next year's Senate elections.

Those being targeted include Representative Steve King, an Iowa Republican thought to be mulling a run for Senate in 2014.

The outspoken conservative has defended Akin's views on rape in the past. The thought of him running in what is seen as a winnable state has spooked mainstream Republicans, who fear his views could lead to another loss.

Quoted in the New York Times on Sunday, Steven Law, president of American Crossroads, said: "We're concerned about Steve King's Todd Akin problem."

He added: "This is an example of candidate discipline and how it would play in a general election. All of the things he's said are going to be hung around his neck."

American Crossroads was set up in 2010 by former Republican National Committee chairman Ed Gillespie and ex-White House strategist Karl Rove as a fundraising entity to help raise cash for party candidates.

The so-called Super Pac is the result of a supreme court ruling of that year that scrapped limits on the amounts that individuals can donate in campaigns.