Eir has pulled out from the National Broadband Plan bid.
The board of the company cited a number of issues behind the decision in a letter to Communications Minister Denis Naughten.
It leaves just one bidder in the running for the State broadband contract, enet.
Last year Siro - a joint venture launched by Vodafone and the ESB - also pulled out of the process.
However, Minister Naughten says the Government hasn't been put over a barrel by Eir pulling out of the bidding process.
There are fears the sole bidder may jack up the price they want from Government to deliver broadband around the country.
Minister Naughten says that won't be the case:Currently, eir is rolling out high speed broadband to over 300,000 premises in rural Ireland.
Minister Naughten said this rollout is the subject of a binding agreement, "whereby eir has committed to building high speed broadband infrastructure to serve these 300,000 premises."
He said eir has reconfirmed its commitment to this commercial investment, as well as their ongoing investment in broadband nationally.
The remaining bidder, the enet-SSE consortium, has confirmed its "continued commitment and engagement" with the Department of Communications on the National Broadband Plan (NBP).
The National Broadband Plan was published back in August 2012.
The Government-wide initiative was to deliver high speed broadband services to all businesses and households in Ireland.
This was to be achieved through a combination of commercial investment by the telecommunications sector and State intervention in those areas where commercial providers acting alone will not provide this essential service.
Sinn Féin communications spokesperson Brian Stanley claims the process is now "in tatters".
"Eir’s shocked withdrawal from the National Broadband Plan means Government plans to connect every home in the state to high speed broadband is in complete chaos.
"This is on the back of the withdrawal last year of Siro leaving then just two bidders left, Eir and enet.
"This now means that the privatisation option has proven flawed. We warned government consistently of the flaws in the whole procurement system.
"One of the worst aspects of this whole process is that Eir were allowed to cherry pick the 300,000 ‘easy to reach’ households in rural Ireland."
Fianna Fáil communications spokesperson Timmy Dooley said the writing was on the wall for the plan as soon as Siro decided to pull out.
"Some people believe that the Government has complicated the process so much that it has become next to impossible for potential bidders to respond in a commercially viable way.
"The question that Government need to answer is are they serious about rolling out broadband to rural communities, and are they prepared to pay for it?
"This represents an unmitigated failure on the part of government, and leaves over 540,000 households in serious limbo", Deputy Dooley said.
And Green Party leader Eamon Ryan said: "To lose one bidder for the national broadband scheme was unfortunate.
"To lose two is carelessness. The Government are asleep at the wheel, and the whole scheme has been thrown into disarray."