By Robert Windrem
NBC News investigative producer for special projects

Yemeni President Ali Abdullah Saleh appears to be left “with not a lot of good options” after his vague promise to peacefully transfer power on Thursday fell flat and may be on the verge of resigning, U.S. officials say.  

Khaled Abdullah / Reuters file

Yemen's President Ali Abdullah Saleh.

Saleh, who has ruled Yemen for 32 years, tried to "tone everybody down" with his offer, contained in a statement aired on the Al Jazeera news channel. But the statement gave no indication of when he would surrender power or whether there were any conditions, and the situation is “way beyond that,” said the U.S. officials, speaking on condition of anonymity. 

One official described Saleh as having "cut and run potential," adding, that "half his brain is telling him to go." 

Facing mounting protests and with his top general siding with protesters demanding democracy, Saleh previously had a new presidential election by January 2012 instead of September 2013, when his term ends.  

Speaking with Reuters, Yassin Noman, head of Yemen's opposition coalition, dismissed Saleh's offer as "empty words" and a spokesman said the umbrella coalition would not even respond. "No dialogue and no initiatives for this dead regime," opposition spokesman Mohammed al-Sabry said. 

Friday opposition groups are planning a "Day of Departure" protest, hoping to get Saleh to leave Sanaa, the capital, and avoid bloodshed. Presidential guards loyal to Saleh clashed Thursday with army units backing opposition groups demanding his ouster. Saleh boosted the presidential guards out of fear that he could be an assassination target. 

Making matters worse for the Arab world's third longest serving leader (only Libya's Gadhafi and Oman's Sultan Qaboos have served longer) were comments from Yemeni Gen. Ali Mohsen, the latest high ranking military man to defect to the side of the mostly young protesters. 

Mohsen, who sent troops to protect pro-democracy protesters in Sanaa, said the options before Saleh were now few, and criticized what he described as his "stubbornness.” He added that the armed forces were committed to protecting protesters. 

He said military rule in Arab countries was outdated and that the people would decide who would govern them in the framework of a modern, civilian state.  The comments led to even more defections. 

A U.S. official said that Washington would prefer Saleh step down because "cut and run leaves the government intact" and reduces the prospect for violence in the already tense nation at the southwestern tip of the Arabian peninsula. The U.S. also has interests in continuing its counter terrorism operations in Yemen, where New Mexico-born Anwar al-Awlaki has been advising al-Qaida in the Arabian Peninsula on anti-American operations. 

British Foreign Secretary William Hague told Parliament Thursday that he had received reports that oil companies were withdrawing their staffs from Yemen. Britain said on Wednesday it was temporarily pulling out part of its Embassy team from Sanaa ahead of the protests expected on Friday.

Reuters news agency contributed to this report.