Green Party TD Neasa Hourigan has resigned as the Green Party whip.
It comes as she has voted against the Government four times this evening on a bill about renters.
The bill will extend the rent freeze and ban on evictions until January - but only for some people.
Deputy Hourigan has said she has serious concerns about the Residential Tenancies and Evaluation Bill, and therefore voted for a number of opposition amendments and against the bill itself.
In a statement, the Green TD said: "The Government's legislation does not offer enough protection for renters on eviction due to sale, recognised as a driver of homelessness, nor does it sufficiently recognise the risks posed by the rent arrears accrued during the pandemic.
"I had made my concerns known to my colleagues at the beginning of the week.
"My vote was in line with Green Party policy and the legislation in question was not contained within the agreements made in the Programme for Government."
Deputy Hourigan said she would like to stay as a Green Party TD and an "active member of this government".
The Green parliamentary party will now decide if the Dublin Central TD should face sanction for voting against the Government,
Neasa Hourigan voting against the government for the second time in this block of voting on the Residential Tenancies Bill
— Seán Defoe (@SeanDefoe) July 30, 2020
Deputy Hourigan was one of the negotiators during programme for government talks.
However, she voiced her opposition to the final deal.
Ahead of the Green vote on the deal, she told party colleagues she was voting against it because she felt the document would make homelessness worse.
She also suggested the coalition would be the "most fiscally conservative government in a generation".
