Washington: The first court conviction of a Guantanamo Bay detainee did little to inch President Barack Obama closer to shuttering the island prison, making it increasingly likely his campaign promise will remain unmet when his term expires.

Jurors in New York City on Wednesday convicted Ahmad Ghailani of conspiracy to blow up government buildings in the Al Qaida attacks on two US embassies in 1998, but they acquitted him on more than 280 other charges. He is the only person transferred from Guantanamo Bay for trial since the US began filling the military prison in Cuba eight years ago.

In some ways, the conviction was a vindication for an administration that believes the judicial system established by the Constitution has proved itself capable of handling terrorism cases.

20 years in prison

Predictions of new terrorist attacks and huge police expenses surrounding the trial never materialised. Ghailani now faces 20 years to life in prison, longer than three of the four sentences handed down by military tribunals at Guantanamo Bay.

Despite the acquittals, the Justice Department said it was pleased Ghailani faces up to life in prison and said it would seek that sentence.

But senior officials, speaking on condition of anonymity, conceded that the one-count conviction, combined with big electoral wins for Republicans this month, will make it harder to close the prison.

The administration had hoped for an overwhelming conviction to help ease congressional opposition to Obama's long-stymied plan for moving the detainees to US soil. The administration must notify Congress before any transfer, and Republicans have said they would block such efforts.

"They couldn't come close to getting that done when the Democrats were in charge," said Representative Peter King, a New York Republican who is expected to be the next chairman of the House Homeland Security Committee.

"There's no way they're going to get it now that Republicans are in charge."

Administration officials believe there are only a handful of options for closing Guantanamo Bay:

Prosecute the detainees. Some, like Ghailani, could face criminal trials. Others could face military commissions. Regardless, the administration wants those trials in the US, not at Guantanamo.

Transfer some prisoners to other countries. Many already have been cleared for release. But Yemeni citizens make up the largest contingent, and the US doesn't trust Yemen to monitor them if they are released. Two failed airline bombings originating in Yemen in the past year have made such release efforts even more difficult.

Hold prisoners indefinitely. Top administration officials have said they don't like the idea but would consider it in some form, if the detainees were held inside the US with some review by courts.

Ghailani's conviction does not make any of those options easier.