TONY Abbott has pleaded for calm after a Liberal MP threatened the independents who will decide the next government, accusing them of holding the nation to ransom.

In an outburst that will undermine Tony Abbott's chances of forming a stable government, Liberal Alby Schultz unleashed on the rural independents.

Mr Schultz rang two of the independents, telling them to pull their heads in and support the Coalition.

The call to Tony Windsor was so threatening that Mr Abbott had to apologise to the Tamworth-based MP.

This morning, Mr Abbott said he had urged fellow coalition MPs not to pressure or heavy the independents.

"We have some very robust independent-minded members of the coalition and Albie is certainly one of them,'' he told ABC television.

"But the point I keep making is that everyone has got to be treated with respect. No one should be pressured or heavied and that is the counsel I am giving to everyone."

Adding to Mr Abbott's problems, one of the other king- makers, Rob Oakeshott, accused Nationals leader Warren Truss of allowing a smear campaign against him.

Mr Oakeshott issued an ultimatum to Mr Abbott: "It's time to step up. Does he want to be PM or not?"

He told The Sunday Telegraph Mr Abbott could "forget" forming a government if he was unable to rein in his MPs.

Mr Schultz's attack, which he admitted would not please his colleagues, comes after Nationals Senate leader Barnaby Joyce had a go at Mr Windsor on election night.

"I don't have a problem with them extracting some benefits for their electorates, but to hold the rest of the country to ransom simply because they've got a lot of power is wrong," Mr Schultz said.

"I consider these people as friends. I described them as men of principle, honesty and integrity.

"I still believe that, but they've lost their way. They're getting lost in their own self-importance.

"I can't believe what they're doing. They're strutting the stage with an arrogance I can't believe."

The blue tests Mr Abbott's claim that he is the only leader who can form a stable minority government.

Admitting he would not be popular with his party, Mr Schultz, said: "Somebody's got to say something.

"They have become a law unto themselves. They've lost their credibility; they can't even reach a consensus among themselves.

"Instead of playing games, they should be getting on and supporting the Coalition."

Mr Schultz, an independently minded Liberal known for speaking his mind, said he was infuriated when Mr Oakeshott criticised other MPs for going on holidays and not being in Canberra while negotiations were under way.

"There's been some stupid stuff coming out of them," he said.

"Fancy talking about combining the two parties. I've never heard anything so stupid in my life.

"They've had their moment of glory. It's time to start thinking about where they stand and stop being a disruptive force.

Mr Schultz said he had spoken to two independents and followed up with a repeat call on Friday. He refused to say who he called, but Mr Windsor complained he had been threatened by a Liberal MP on Friday.

"I rang one of them ... and gave them some advice," Mr Schultz said. "It was to say, 'Think seriously about what you're doing.' "

"It could be a black page in the history of Australian politics if they don't do the right thing."

The threats prompted a quick apology from Mr Abbott.

But the Opposition Leader also said today he could not stop exchanges taking place between MPs who were friendly with each other.

"I can't stop mates talking to mates but I say that it should all be done with respect.''