Federal politicians are regularly wagging Parliament to campaign in the WA Senate election.
The two most vulnerable incumbents, Labor's Louise Pratt and Greens Senator Scott Ludlam, chose to stay away from Canberra for parliamentary sittings yesterday.
Taxpayers are also footing the bill for Opposition frontbenchers to fly to Perth during sitting weeks to campaign for Labor's candidates.
Since the Senate-only election was announced on February 28, shadow health minister Catherine King - on March 6 - and shadow employment minister Brendan O'Connor - yesterday - have opted for Perth over Parliament.
Shadow education minister Kate Ellis will skip Parliament later this week to campaign in WA.
Shadow ministers can claim $400 a night in travel allowance when in Perth, as well as charge taxpayers for the cost of the return flight.
Senator Pratt, who lost her seat on the disputed re-count, had her last day in the Senate on March 5. Senator Ludlam has attended just two of the past eight sittings.
Liberal senators David Johnston and Michaelia Cash also missed Parliament yesterday but were not campaigning. Senator Johnston has been on ministerial duties in Perth and Senator Cash was ill.
Senator Johnston was absent last week for defence talks in Indonesia but both ministers otherwise have attended Parliament since the election was called.
"Both senators Cash and Johnston will be in Canberra and Perth during this parliamentary sitting week," a government spokeswoman said.
WA political expert Dr Harry Phillips said politicians' traditional priority should be to attend Parliament rather than electioneer "but it is such an unusual circumstance new conventions are being established".
"If one party takes a different view they can get better publicity being in Perth on that day that is what pushes the envelope and they don't want to concede an obvious advantage," he said.
Labor frontbenchers defended their absence from Parliament.
"If there's one thing I know, West Australians prefer to be talked with in WA rather than yelled at from Canberra," Mr O'Connor said.
Senator Ludlam said he had argued the by-election should be held in May to avoid a clash with sittings.
"I have been back to Canberra during the campaign for some of the sitting days and Budget estimate sessions but it is in WA that the voters are and not Canberra," he said.