The Coalition has slapped down a threat by the family First Senator, Steve Fielding, to try to cripple a Labor government, by refusing to endorse him in blocking supply.

Senator Fielding appears to have lost his seat but will sit in the Senate until June 30.

He claims Labor does not deserve to govern the country and if it forms a minority government, he will use his crucial Senate vote to block all Labor legislation, including its next budget.

However, to be effective he would need the support of the Coalition.

A spokesman for the Coalition leader, Tony Abbott, said if the Coalition were in Opposition, it would not block supply.

The Greens Senator, Bob Brown, further ridiculed Senator Fielding's threat. From July 1, the Greens would assume the balance of power in the Senate.

Even if Senator Fielding succeeded in blocking the budget, the Greens would unblock it on July 1, the day the budget came into effect.

Abbott kills Fielding's threat to block Labor supply