Europe aims to break the Russian stranglehold on the regional energy sector by moving non-Russian gas through the Nabucco pipeline, which forms part of the planned Southern Corridor of planned transit networks.
European leaders said a January agreement with natural gas-rich Azerbaijan was a "major breakthrough" for European energy security and the Southern Corridor.
Stefan Judisch, chief executive officer of RWE, a Nabucco consortium member, told the Financial Times that suppliers needed to come forward as early as March to get the project rolling.
"We now need to have concrete commitments of volumes this quarter," he was quoted as saying.
Christian Dolezal, a spokesman for the Nabucco consortium, told United Press International in response to e-mail questions that supply contracts are the basis for their considerable financial commitment.
"Commitments are good, contracts are better," he said.
Nabucco critics say the project will have difficulty securing adequate supplies, though Judisch brushed off those concerns provided Azerbaijan and others come through.
Nabucco, however, enjoys widespread political support from European member states despite Russia moving ahead with its rival Nord Stream and South Stream projects that avoid politically sensitive transit networks in Ukraine.
Nabucco could start moving gas by the end of 2015.