Mark McGowan's proposed deferral of the new museum to pay for Labor's transport plans would delay the project another decade, arts and culture advocates say.
"This is the idea of a shoddy populist who imagines that the ordinary people of WA don't want first-class educational and cultural facilities for themselves and their children," WA historian Geoffrey Bolton said.
The need for a new museum was identified more than 20 years ago but the project has been deferred repeatedly. The Carpenter government committed $500 million in 2008 to redevelop the old East Perth power station but the Barnett Government canned that.
The last State Budget included $71 million towards the $428 million projected cost of a new museum in the Perth Cultural Centre.
"A new museum for WA is long overdue and it is not only a popular attraction for West Australians but also a key component of cultural tourism," Chamber of Arts and Culture chairman Warwick Hemsley said.