The dominant hard right in the NSW Liberal Party has been pressuring Senator Heffernan, who will be 68 when his term expires in 2011, to bow out of politics at the next election.

But Senator Heffernan plans to stand again and has started visiting Liberal branches throughout NSW to shore up his position against any challenge when the party preselects its next Senate ticket.

Senator Heffernan was close to the former prime minister, John Howard, and has been a strong supporter of the Opposition Leader, Malcolm Turnbull.

While part of the Liberal right, Senator Heffernan is not close to the faction's "religious right" leadership in NSW and has positions at odds with the stance of fellow conservatives on issues such as environmental policy.

Some Liberals believe the hard right, led by the NSW state MP David Clarke, is determined to drop Senator Heffernan into the unwinnable No.4 position on the Liberal-National NSW Senate ticket.

"The right have control of the numbers for the Senate preselection and that will make Senator Heffernan's position reasonably tenuous," said one NSW Liberal MP who did not want to be named.

But hard right figures deny they are planning to unseat Senator Heffernan. They say the role of local party delegates in NSW Senate preselections means factional numbers cannot be wielded in a centralised way.

A panel of about 115 selectors, mostly from local branches, will choose the party's candidates after an electoral redistribution due to be finalised this year.

Each of the Liberal Party's 49 NSW federal electorate conferences sends two delegates to this panel.

"It is very hard to unseat a sitting senator and to succeed there need to be two elements: the sitting senator has to be vulnerable and there has to be a viable alternative candidate," said a NSW Liberal from the hard right.

If the hard right is unable to field a strong candidate against Senator Heffernan, it may concentrate on securing the No.1 ticket position for Senator Concetta Fierravanti-Wells.