Democrats on the Senate Rules Committee foiled a Republican move last night to prevent or postpone disclosure of the amount each senator spends on government-paid mass mailings -- information that could prove politically damaging.

When the time came for a vote, after more than a day of delay, not enough Republicans were present to support a motion by Sen. Ted Stevens (R-Alaska) to delay disclosure, scheduled for this month. He was forced to withdraw the motion before a roll call could be taken.

Earlier this year, the Rules Committee approved regulations requiring publication of the cost of each senator's mass mailings. The fee ran as high as $3.8 million for one unidentified senator in 1984, and costs are estimated at $144 million in 1986 for the entire Congress.

The House has no disclosure requirement, and in an effort to force House members to disclose franking costs, the Senate committee approved a measure last night binding both chambers to reveal specific mail expenses to the public. The action appeared to be primarily symbolic, however, since the House is not expected to act on it.

As the Senate's Nov. 29 publication deadline has approached, a growing number of members have become concerned that public disclosure of mail costs could be used against them in political campaigns. In 1986, the seats held by 22 Republicans are up for election compared to 12 seats held by Democrats.

Last night, all but one of the Democrats on the Rules Committee showed up to reiterate their support for releasing the information. "We are going to stand where we are," a smiling Sen. Wendell H. Ford (D-Ky.) told Republican members of the panel.

Although a majority on the panel, only four Republicans appeared for the session, and one of them, Sen. Charles McC. Mathias Jr. (R-Md.), is a proponent of disclosure.

Stevens, the leader of the drive to postpone disclosure, said he would take the issue to the Senate floor in a last-ditch effort to put off publication of the data on individual mass-mailing costs.

Saying he is not opposed to disclosure, Stevens said the requirement will "hold the Senate up for disrepute" while members of the House escape scrutiny.