Prime Minister Malcolm Turnbull is being squeezed hard on same sex marriage. Picture: Jeremy Piper

The biggest danger to Malcolm Turnbull’s leadership is not legislation to approve same-sex marriage.

It’s the drive for an expensive, non-binding, voluntary plebiscite of dubious credibility which would never be agreed to by this Parliament.

In the bizarre jumble of priorities being prosecuted by some sections of the Coalition, the battle for the possibly useless national ballot is occupying scarce energy just as Labor ramps up a strong appeal to its constituency and beyond.

The debate now distracting the Liberal Party is not the proposal for a parliamentary vote on the Marriage Act. It is the insistence on something else by a small group of no-holds-barred, right-wing agitators who are determined to undermine the Prime Minister.

There are two factors identified by this disruption.

One is the disrupters recognise that a bill to allow same-sex marriage would pass if it was put to Parliament, and there would not be protests in the street. Voters just want it settled.

So their only option is legislative procrastination; serial delaying tactics.

Opposition Leader Bill Shorten is pushing hard.Source:AAP

They are being confronted by a growing and articulate group of MPs, some of them conservatives, who want the same-sex marriage matter decided by Parliament and they are being outargued. So the agitators are switching the debate topic to the plebiscite.

They are claiming this remains binding election policy, although other parts of the election manifesto rejected by Parliament have been reshaped.

Second, this group is using the blunt instrument of the same-sex marriage plebiscite debate to wound and even remove Malcolm Turnbull as leader, and consequently heighten the risk of the Coalition losing the next election.

And through their usual media outlets they are making this known.

“It is chaos and mutiny in Canberra, let me assure you. I have spoken to Senior Cabinet Ministers who tell me Turnbull is gone,” tweeted broadcaster Alan Jones today.

Labor has vigorously demonstrated that divided parties don’t survive in government.

We are two years out from a scheduled election. Change the prime ministership and it will come sooner.

The no-holds-barred tag is well earned. According to some reports today the party rule book is being rewritten.

Gay Liberal MP Trevor Evans has signalled he may cross the floor over the issue. Picture: Lyndon MechielsenSource:News Corp Australia

The agitators have sent the message that the proud Liberal tradition of a right to cross the floor is suspended on the same-sex plebiscite matter.

And if MPs — apparently gay MPs in particular — speak out in favour of Marriage Act changes or for a parliamentary vote, they could lose preselection as candidates.

Tony Abbott was allowed to give a closed-door address to a Liberal branch in which he unabashedly attacked his own side’s May Budget, while others publicly commenting in favour of same-sex marriage are somehow party traitors.

Again, the target is Malcolm Turnbull who on Monday said: “In our party back benchers have always had the right to cross the floor. In the Labor Party you get expelled for doing that, but it has always been a fundamental principle in the Liberal Party and indeed the National Party.”

Once a Coalition boast, now fighting words.