A U.S.-Canadian task force essentially has completed its interim report and will cite a number of causes, not merely a single event, for the massive power blackout last August, Energy Secretary Spencer Abraham (search) said Monday.

The findings of the task force could come as early as next week.

In an interview, Abraham would not give specifics because some details of the report still must be cleared up with the Canadians. He made clear, however, that no single smoking gun will be cited as the cause of the Aug. 14 blackout (search) that darkened all or parts of eight states from Michigan to New York and into Canada.

"I think you're going to see there are a number of factors that emerged during this investigation as being ... causes or partial causes," Abraham said in the interview with The Associated Press.

"We are not going to be focused on a single event. ... We will be looking at more than one," he said.

On other matters Abraham:

-- Said it is essential for Congress to finish an energy bill (search) this year, and he's "not going to give an inch of ground on that." He said the inability of Congress to produce energy legislation over the past three years has hurt energy investment because of a cloud of uncertainty.

-- Expressed uneasiness that the Russian government's actions to freeze stock of the country's largest oil company, Yukos, might dampen enthusiasm among U.S. and other Western companies who had been ready to invest in Russia's energy sector.

"These companies are obviously going to watch very closely what transpires," said Abraham.

-- Said he and Russian Atomic Energy Minister Alexander Rumyantsev will meet this week and announce a joint venture between U.S. and Russian companies to manufacture highly specialized medical devices. The venture is part of an effort to find jobs for former Russian nuclear scientists.

Abraham said the U.S.-Canadian task force investigating the blackout has been scrupulous in trying to be accurate in its findings, but will open its interim conclusions to a review by other parties, who might want to challenge some of the conclusions. Those suggestions would be considered before a final report and recommendations were issued this the year, he said.

Investigators have concluded that many of the problems on the day of the blackout began in Ohio, where a number of power lines belonging to First Energy Corp. failed during the hour before the power outage hit full force.

Investigators also have been examining what influence a number of independent power producers, who were pumping large amounts of electricity through northern Ohio lines on the day of the blackout, might have had on the system. One theory has been that the system suffered from a shortage of so-called reactive power, essential to maintain voltage needed to push electrons through the system, because the independents might not have been producing enough of it.

Recently, the North American Electric Reliability Council, while not commenting directly on the investigation, reminded grid operators of the importance of maintaining adequate levels of reactive power to maintain voltage. The NERC advisory also reiterated the need for better communications and system monitoring, issues known to have been of interest to the blackout investigators.

On energy legislation, Abraham acknowledged the administration can go only so far in trying to get two powerful Republican lawmakers -- Sen. Charles Grassley of Iowa and Bill Thomas of California, the primary tax writers in Congress -- to resolve their sharp differences over an ethanol tax proposal. The ethanol problem has hamstrung the energy talks for more than a week.

Abraham said there is a point where senior lawmakers will resist "when it looks like the White House is trying to strong-arm them." He said the administration is "trying to walk a thin tightrope" and help congressional GOP leaders compromise.

"I think we're doing what is the right level of prodding at this point," he said.