The Liberal Party is considering new rules to disqualify candidates who disobey instructions and run their own rogue election campaigns, following the "dishonourable" performance of spurned Senator Jim Molan.

Liberal MP and former party president Trent Zimmerman said while Senator Molan's "below-the-line" campaign to be re-elected did not breach any rules, it disrespected the Liberal Party and undermined its coalition agreement with the Nationals.

Outgoing Liberal senator Jim Molan at a Coalition party room meeting in Canberra on Tuesday. Credit:Alex Ellinghausen

Senator Molan, whose term expires on June 30, was relegated to an unwinnable fourth position on the Coalition's Senate ticket in NSW at the May 18 election. In response, he mounted his own campaign asking supporters to give him their first preference by voting below the line on their ballot paper rather than following official Liberal how-to-vote cards.

Critics accused him of confusing voters and undermining the Coalition's campaign by recruiting Liberal volunteers to wear "Jim Molan" T-shirts and hand out his how-to-vote cards when they should have been supporting other Liberal candidates.