The Senedd has called for the Six Nations to remain in a protected list of free-to-air TV events.
A Tory MS said it would be a "major mistake" for the tournament to go behind a paywall.
But it comes despite the Welsh Rugby Union warning such a move could devastate Welsh rugby.
All Senedd parties agreed with the call for the tournament to be protected by the UK government in a debate on Wednesday.
A motion tabled by the Welsh Conservatives was agreed unanimously without a vote.
The UK government, recently rejected such calls., which have been prompted by fears the live event could become subscription only once a BBC and ITV deal ends next year.
But last year a Conservative minister told a committee that if the Senedd could make a strong case, then the matter was not necessarily closed.
Welsh politicians are hoping it will be added to the group A list of events, which are offered to the main free-to-air broadcasters on "fair and reasonable terms".
Currently the Six Nations is in group B, which can go behind a paywall as long as there are free-to-air highlights.
Meanwhile, the Welsh government is under pressure to ease the terms of a loan the union has with ministers.
In the debate, Tom Giffard urged MSs to back the call for the Six Nations rugby to remain free-to-air when the current deal with the BBC and ITV runs out next year.
He said: "Those communal moments that we enjoy together as a nation, that bind us together as people, are literally priceless that's why it would be major mistake for Welsh rugby and for Wales to put the Six Nations behind a pay wall".
Plaid Cymru's Heledd Fychan said her party would back the call from Welsh Conservatives MSs for the Six Nations to remain free-to-air but she said this was not being supported by Conservative MPs.
"We don't have the power to decide this here... but why aren't Tory MPs in Westminster standing up for Wales" she said.
Labour MS Alun Davies said the Six Nations and international rugby "created the heroes of tomorrow and the role models for today".
The Conservative Laura Ann Jones said free-to-air Six Nations allowed "the flame to be lit in Welsh children across our nation, inspiring the next generation".
The Welsh government's deputy sport minister Dawn Bowden said the tournament "must remain free-to-air so the majority of the Welsh population are able to view the games".
But she said it was important "we recognise the difficult position of the Welsh rugby union who can't make this decision unilaterally".
'Negative financial implications'
In a letter to the Senedd's culture committee, WRU chief executive Abi Tierney said: "Put simply, the negative financial implications of moving international rugby matches in the Six Nations Rugby Championship to the protected list could have a devastating impact on the whole of the game in Wales in the medium and long term.
"Of course, Welsh rugby holds a unique and special place in our national culture... But we also have responsibility to ensure that both the professional and community games in Wales are sustainable."
Ms Tierney said that over the past five years, 26% of the WRU's income has come from broadcast rights.
She continued: "We need to retain the option to broadcast on subscription services, in order to keep the existing tension in the market.
"Of course, we do not wish to diminish the reach of our game. To the contrary, we need and want to be seen, but there is a balance to be struck."
Abi Tierney and WRU Director of Rugby Nigel Walker will appear in front of the sport and culture committee on Thursday.