Railroad unions, still fuming about a proposal to overhaul the Railroad Retirement System, have told Vice President Albert Gore that any changes in the status quo are a bad idea and should be abandoned.

Unions already are asking their 1.3 million members and retirees to flood Congress with mail if Mr. Gore's National Performance Review group doesn't back down on proposing the changes, with one group mailing out more than 100,000 letters last week.The threat of political opposition has brought a tentative offer from the vice president's office that Mr. Gore may meet with union leaders later this week. Mr. Gore scheduled a similar meeting last week, but sent a mid-level assistant at the last minute, a substitution that didn't smooth any ruffled feathers.

The report developed by Mr. Gore's group proposed changes that would transfer administration of the Railroad Retirement Benefits Board to other agencies.

Those proposals also would have altered the industry's unemployment insurance system, and possibly privatized management of a benefits fund that generates monthly checks for more than 1 million railroaders, retirees and their families.

Rail unions had attempted to convey their unhappiness to Mr. Gore's office before the "reinventing government" report was unveiled at the White House earlier this month. A letter sent to the vice president last week spelled out the unions' anger in no uncertain terms and set a deadline for a response.

"If we do not receive a response by 12 noon (Sept. 17) we will assume that the administration is supporting the railroad retirement system changes that are contained in the NPR. If this occurs, we have no alternative but to begin to rally the 1.3 million citizens who will be negatively affected by the administration's action," Leroy Jones, national legislative director for the Brotherhood of Locomotive Engineers, wrote to Mr. Gore.

The union's president, Ron McLaughlin, chairs the unions' umbrella representative group, the Railway Labor Executives Association.

The vice president's office late Friday apparently asked for a grace period of a week to respond before the rail labor community goes public with an organized protest, a request the RLEA has agreed to honor.

However, the National Association of Retired and Veteran Railway Employees Inc., has sent a letter asking members to contact members of Congress, and several individual unions are proceeding with the public relations campaign.

Mr. Jones said unions and retirees oppose the proposal because they believe the existing system operates more efficiently than Social Security, spends no federal dollars and would create major problems in unemployment insurance.

Train crews often work in three or four states on a single run, which would create a dilemma about where workers could file for benefits, he said.

In addition, Mr. Jones said unions felt "really insulted" that an administration they worked hard to help elect would adopt strategies previously proposed by the Presidents Reagan and Bush.

The Association of American Railroads is publicly taking a low profile on the issue. A spokeswoman said it was difficult to respond to the report's recommendations because they were not specific or detailed.

Ed Harper, AAR president, wrote to Mr. McLaughlin, expressing puzzlement over the administration's vague proposals, opposition to any "radical change" and an offer to get together and exchange information and work in tandem.