There are fears the ill-fated National Broadband Plan could cost more than €3 billion - six times the original estimate for the state programme.
The Irish Times says officials are now working on a 'plan B' in case the whole project collapses.
Rollout of the plan was put in jeopardy earlier this month when Communications Minister Denis Naughten resigned after controversial meetings with one of the bidders for the tender.
Plans to extend high-speed broadband across the country have been delayed since 2012.
Rural broadband is expected to be a key element during the confidence and supply agreement talks that are underway between Fine Gael and Fianna Fáil.