Fianna Fáil says the tender process for the National Broadband Plan has "absolutely failed".
It comes amid reports the Government is due to approve the plan - despite the cost going significantly over budget to €3 billion.
The plan aims to bring high-speed Internet to more than 500,000 homes and businesses waiting for access to broadband across the country.
The last remaining bidder is a consortium led by businessman David McCourt.
According to The Irish Times, Cabinet is likely to be asked to sign off on the plan the week after next.
However, Fianna Fáil's communications spokesperson Timmy Dooley is calling for more engagement with the other bidders who pulled out earlier in the broadband plan tender process.
He observed: "It now clearly points out that the tender process that the State put in place to identify a bidder that would provide a service and value for money for the State has absolutely failed.
"It failed around 18 months ago... when two of the main competitors pulled out of the race. It was clear at that stage that there was only going to be one outcome."
He added: "I think it was unwise for the past 18 months to continue with the process without engaging without the two major players that pulled out.
"To the best of my knowledge there has been no serious engagement with either the ESB, Vodafone or Eir - I think that was a fundamental mistake on behalf of the Government and its agents.
"I still don't think it's too late for a detailed engagement with the ESB in particular."
Taoiseach Leo Varadkar confirmed earlier this month that the cost of the National Broadband Plan could be around €3 billion over 25 years.
He said: "Bear in mind the benefits - 540,000 homes, farms and businesses... over a million people... a huge project of huge scale."
The original cost of the broadband plan was projected to be half a billion euro.
