Montgomery County Executive Sidney Kramer, standing firmly behind his plan to allow up to 13,500 new jobs in downtown Silver Spring, said yesterday he was surprised by Planning Board Chairman Norman L. Christeller's call for a cutback in development because Christeller previously had endorsed the plan.

Kramer, in a telephone interview in which he barely concealed his frustration with Montgomery's controversial planning chief, said that he scaled back his original proposal of 15,000 jobs after Christeller told him the recommendation of the planning staff was 13,500 jobs.

"He asked if I could accept 13,500," Kramer said, explaining that he agreed because "it was not a sufficient difference to argue over and it would be good if the council were presented with a single position."

Christeller's stated position Monday that he would support the addition of only 10,000 jobs poses a serious threat to Kramer as he tries to win County Council approval for a plan that carries huge political risks but which he has made a priority of his first-term administration.

Christeller, who has been planning chief for more than six years, is widely regarded as a formidable opponent with an encyclopedic knowledge of county land use and a no-holds-barred approach to political battles.

"When you go to the mat with Norman, you know going in {that} the odds are probably against you," said one council source.

The ceiling on the number of jobs, a county method to control development, has emerged as a key issue in the debate on Silver Spring, coming to symbolize the scale and pace of future building projects. Opponents of Kramer's ambitious plan for a commercial and residential revitalization of the aging downtown say the plans are too massive and will cause neighborhood-choking traffic.

In Christeller's tenure as head of the Planning Board, there have been rocky relations between him and the executive branch. The most explosive was Christeller's vigorous but unsuccessful battle to prevent changes in state law giving the executive more planning powers, including the right to appoint two of the five board members. Some sources close to the administration suggested yesterday that that lost battle lies at the heart of Christeller's Silver Spring decision.

"I know for a fact that Mr. Christeller very vigorously resisted that modification {in state law}, but whether there are any lingering antagonisms, only he can answer," said Kramer.

"I don't know of any hard feelings on our part," Christeller said yesterday. He said his decision to support 10,000 new jobs is based solely on his concerns about traffic. "I have to tell you," he said, "that no one has spent more time trying to understand the ins and outs of these issues than I have . . . certainly as much time as Mr. Kramer."

Christeller disputed Kramer's version of events, saying that, while he was one of three board members to endorse 13,500 jobs in July, he also made it clear there was a lot of uncertainty that could change the board's thinking.

"I told him I would vote for it, but I wanted more information on several aspects," Christeller said, explaining that additional data raises even more doubts about Kramer's plans.

Christeller said he told Kramer of his reservations in a telephone call and in a letter. Kramer countered that he and Christeller had spoken several times in recent weeks and Christeller did not mention his concerns, nor did he mention the 10,000 jobs figure before going public.

Kramer also said he thought that Christeller, as chairman, had an obligation when the County Council starts work sessions Thursday to represent the position of the majority of the board, which has indicated it is split 3 to 2 in support of the 13,500 figure. Christeller said Monday that one of the three members who support Kramer's plan should present that view to the council and he would defend the minority view. The board's opinions are advisory to the council, which is expected to make a final decision on the Silver Spring plans this fall.

Kramer's reputation as lawmaker and executive is to try to reach a common ground. He said yesterday that style still applies, but when asked a range of jobs on which he would compromise, Kramer responded, "My range is 13,500."