A campaign is underway to have the Premier reschedule the upper house polls for Windermere, Derwent and Mersey, separate to the lower house equivalent on the 1st of May.
Six Legislative Councillors, including traditional foes Ruth Forrest and Ivan Dean, have signed a letter about the unprecedented overlap.
They're concerned it will give party candidates an unfair advantage over independents, while compromising the role of the Legislative Council.
"Your decision to align Legislative Council and House of Assembly election dates for the first time in the history of the Tasmanian Parliament risks undermining the important and separate role of the Legislative Council in holding the Government of the day to account," the letter read.
"It is key to a healthy democracy."
Nelson Independent Meg Webb also signed the letter, and says the Upper House must remain largely independent.
"The Upper House has a really different role to the Lower House," she said.
"It's a House of review, it's the House that holds the government of the day to account, whichever political stripes that government may be."
But Ms Webb stopped short of accusing the Liberals of deliberately orchestrating the situation.
"It's unfortunate that they've put themselves in the position where we even have to ask the question, has this been done out of self-interest for the Liberal party?"
The letter is also signed by Rob Valentine, Tania Rattray and Rosemary Armitage.