Mayor Stephanie Rawlings-Blake has opened an imposing lead over her challengers with just weeks to go before the Democratic primary, garnering a larger share of likely voters than all of her rivals combined, according to a Baltimore Sun poll.

Sixty-eight percent of the respondents approved of the job Rawlings-Blake has done as mayor since she took office last year, and half of those polled said they plan to vote her back for a full four-year term.

"She looked at the city's problems and she handled them in a direct manner," said Lawrence Gray, a retired analyst with the Social Security Administration. "She didn't try to fool anyone with the sacrifices that would have to be made by the city."

The rest of the field managed only 32 percent combined.

State Sen. Catherine E. Pugh and former city Planning Director Otis Rolley were in a statistical tie for second place, with 12 percent and 10 percent, respectively. Clerk of Court Frank M. Conaway Sr. and Joseph T. "Jody" Landers, a former vice president of the Greater Baltimore Board of Realtors, each had 5 percent.

Rawlings-Blake also has enjoyed advantages in fundraising, cash on hand and endorsements from the Democratic establishment. In a city dominated by the party, the winner of the Sept. 13 primary is all but assured of victory in November.

The telephone survey of 742 likely Democratic primary voters was conducted Aug. 22-24 by OpinionWorks of Annapolis for The Baltimore Sun. The opinion poll has a margin of error of 3.6 percentage points.

The numbers are daunting for Rawlings-Blake's challengers, pollster Steve Raabe said.

"It's a big margin for somebody to make up, and there isn't a clear second-place candidate," said Raabe, president of OpinionWorks. "If there is some movement away from the mayor in these closing days, it's not clear that that would gravitate toward one alternative candidate.

"That's probably the problem for the competitors — whatever vote there may be out there that is in opposition to the current mayor is going to get divided."

Rawlings-Blake, who took office in February 2010 after Mayor Sheila Dixon resigned as part of a plea deal to settle charges of theft and perjury, leads among nearly every racial group, age category and education level, according to the poll.

Rolley won the support of 24 percent of likely primary voters under age 35; Rawlings-Blake received 21 percent — a statistical dead heat.

Rawlings-Blake supporters are more ardent than those of other candidates, with 65 percent saying they were firm in their decision.

Rolley backers expressed the second-highest level of dedication, with 49 percent reporting firm support.

In another possible glimmer of hope for Rolley, 21 percent of his supporters said they had decided to back him "in the last day or two" — a significantly higher percentage than for any other candidate.

"If anyone in the race has a little bit of momentum, it's probably him," Raabe said.

Gray, the retired Social Security analyst, said he was skeptical when Rawlings-Blake was sworn in.

"Nobody even knew who she was," said Gray, 65, who lives in the Southwest Baltimore neighborhood of Beechfield. "She was just there as a result of being in the right place at the right time. And with all the shenanigans that went on down there in City Hall, I thought she fell in with it. "

But he said Rawlings-Blake's approach to closing significant budget gaps two years in a row earned his trust.