CHICAGO (AP) _ Democratic vice presidential candidate Lloyd Bentsen said Sunday that the presidential campaign, no matter who wins, will not leave the next president with a ''serious mandate.''

That ''means more work and a lot more swabbing that has to be done, and I think Mike Dukakis can do that,'' he said of his party's standard-bearer.

Bentsen appeared on both NBC-TV's ''Meet the Press'' and on CBS-TV's ''Face the Nation.'' NBC said Republican Dan Quayle had also been invited but turned down the invitation, and journalists on the show said Quayle had appeared on no national television interview shows during the campaign.

On CBS, Bentsen predicted that congressional Democrats would not gang up on Bush if Bush were elected.

''Not gang up, no, but I don't think he gets any brownie points (from) the kind of campaign he's run. It's been an extremely negative one,'' the Texas senator said.

Bentsen reiterated his indignation at the Republican's negative advertising.

''They've had an effect and they've hurt and they demean the process,'' he told NBC. Bush's wife and one of his sons defended the vice president on CBS. ''You can't persuade me that George has run a dirty campaign,'' said Barbara Bush. ''He hasn't.''

Jeb Bush said Dukakis was ''fair game'' and he didn't expect his father to face resentment if elected. ''My dad has a great ability to heal wounds,'' he said.

Bentsen, asked if Bush would find a stalemate greeting him because of a lack of a mandate on specific issues, said: ''Frankly, I don't think either candidate at this point has a serious mandate.''

Afterward, he told reporters, ''Michael Dukakis will not have as much of a mandate as he deserves because it was difficult to get the issues across with all the clutter of negative advertising. But I also believe the two of us together, with me as vice president ... that we will be able to get our legislative program through better than George Bush and Dan Quayle would.''

Bentsen said that if he returned to his post as chairman of the Senate Finance Committee, he would not try to use that forum to wreak vengeance on Bush.

''We have to much at stake in this country to try to seek revenge or something like that,'' he said. ''We're on a mountain of debt in this country, and our budget deficit and our trade deficit, and those things have to be turned around.''

''I'd work with any president, for my country. I'd help when I thought he was right, and I'd try to block him when I thought he was wrong,'' Bentsen said. ''That's what I hired out to do.''

Asked to look at 1992 if the Republicans won this time, the 67-year-old Bentsen declined to say if he'd run for president.

''I believe in 1992 ... I'll be running for vice president and Mike Dukakis will be finishing a first and successful term of office,'' he said.

When reporters asked him later if this was his last campaign, he joked, ''What do you mean, a kid like me? I've been in politics long enough to know to never say never.''

Bentsen headed back to his home state of Texas after appearing on the network interview shows in Chicago.

Bush strategist and pollster Robert Teeter said his surveys showed Texas, the state that Dukakis chose Bentsen to help win, was firmly in Bush's column and a statewide newspaper poll backed up that assertion.

A survey sponsored by the Dallas Morning News and the Houston Chronicle gave Bush a 56-39 lead in Texas. The survey had a four-point margin of error.

''If they had it all locked up, why is the Bush-Quayle campaign dumping a half million dollars in negative ads'' in the state, Bentsen said at a rally in Corpus Christi. President Reagan's stop in the state and Republican Party spending were also evidence it was close, he said.

''Let's go flat out for the next couple of days,'' he told the crowd of about 800 in the local civic center.

In El Paso, Bentsen told a rally outside the city's train station that the Democrats are concerned about the middle class - a theme Dukakis has been hammering in his campaign stops.

''Mike Dukakis and Lloyd Bentsen are on the side of the working men and women of America and the Republicans are on the other side,'' said the Democratic candidate, who addressed the crowd in both Spanish and English - an appeal to the state's large Hispanic population.

As Bentsen's motorcade worked its way through the streets of El Paso, citizens honked their car horns with approval.