A great silence has descended upon the White House in this last week before the congressional elections.

President Carter was supposed to have a nationally televised news conference yesterday. It was canceled Monday afternoon, on the grounds that for the moment, the less said on a number of sticky public issues, the better.

The president's spokesman, Jody Powell, does not enjoy the luxury of being able to cancel his daily White House news briefings. But while Powell may be questioned, he cannot be forced to answer, as the following exchanges from Monday's briefing demonstrate:

Question: "Can you tell us what is in the note from Prime Minister Begin in reply to the president's note on the settlements issue?"

Powell: "No."

Question: "Do you have any comment from the White House's view on the difficulties in Iran . . .?"

Powell: "I don't have any comment on that."

Question: "Do you know anything about the situation there?"

Powell: "In Iran? I don't have anything on it at this point."

Question: "Do you have anything on the continued decline of the dollar and the stock market?"

Powell: "I don't have anyting to add to the comments that the Secretary of Treasury made at his last press conference."

Question: "When was that?"

Powell: "I don't remember the exact day. It was in the past few days."

Question: "Anything new on the tax . . ."

Powell: "No."

So it goes. Yesterday's briefing was more of the same. On most issues - the Middle East peace negotiations, the deteriorating situation in Iran, the decline of the dollar and what that says about foreign confidence in Carter's anti-inflation program - Powell usually replies, as he did yesterday, that "I have nothing generally on the subject."

In an interview, the press secretary said it was "coincidence," and not the impending elections, that led to his recent bashfulness in answering questions.

"There is just not much to be said about the two main topics of the day," he said.

The Middle East peace negotations, Powell pointed out, are being handled by the State Department, which is holding its own daily briefing for reporters coving the talks. As for the dollar, he said that "for obvious reasons, that is something you don't fool around on" with a lot of talk.

The elections, however, were a factor in the decision to cancel the president's news conference - making October one of the few months in which Carter has not had his customary two news conferences.

White House aides feared that Carter would be unresponsive on most political questions or, if not, would open himself to charges of using the news conference as a partisan forum.

The president's next news conference is now scheduled for shortly after Tuesday's elections. Powell has not announced when he expects to become more forthcoming.