With 18 days till the election, Michael Dukakis said on network talk shows Friday he is counting on more TV exposure to give voters "a better sense of who I am." Rival George Bush declared he wants to be remembered as the president who helped ban chemical weapons.

Dukakis, who has been campaigning for more than 11/2 years, said Friday that voters are only now "beginning to focus in" and make their decisions. He said he was cautiously optimistic about his chances though "we're behind a little bit." Polls have shown him trailing Bush.He has been striking back harder at Bush's allegations in recent days, and he complained anew Friday on "CBS This Morning" that "I've been subject to attacks and distortion.

"The American people are not happy with this campaign," he added on ABC's "Good Morning America.

"I hope through interviews like this, people will have a better sense of who I am," he said on CBS.

Peace broke out briefly Thursday night between the two presidential candidates, who appeared jointly at the Alfred E. Smith charity dinner in New York, a state where Republicans say Dukakis' once-strong support is shaky.

But behind the scenes, Dukakis was apologizing directly to the vice president for remarks made by a campaign worker about Bush. The official, national field director Donna Brazile, resigned Thursday after telling reporters that Bush should "fess up" about rumors involving his personal life.

In Toledo Friday, Bush spoke out strongly against "this terrible scourge" of chemical weapons, said they had been used in the Iran-Iraq war and spelled out steps he said could lead to an effective ban.

He proposed making nations guilty of chemical warfare pay "a heavy penalty . . . the censure of all nations." He called for on-site inspection of suspicious facilities or plants and tightening controls on the transfer of chemical technology and weapons.

"If I'm elected president, if I'm remembered for anything, it would be this:a complete and total ban on chemical weapons," Bush said. long-stated goal of aworldwide ban on biological and chemical warfare.

Elsewhere Friday, President Reagan returned to the campaign trail on behalf of his vice president, saying in Bowling Green, Ky., that Bush has shown how to "keep a cool head in hot crises."

Dukakis stayed in New York Friday to tape a pair of TV talk-show interviews, and spent most of the day in that state before going to Louisiana and Texas. The two Southern states are considered the Democrat's best prospects in the region.

At the Al Smith dinner, a nonpartisan Catholic charity event in New York, Dukakis spoke first and got in a few jibes at Bush as well as some self-deprecating digs at himself.

"Mr. Vice President, I am glad to see you here tonight," the 5-foot-8 Dukakis told his 6-foot-2 counterpart. "You've said you want to give America back to the little guy. Mr. Vice President, I am that man!"

The crowd roared, and it chuckled when Dukakis drew parallels between himself and the man remembered at the dinner; Smith stood 5-foot-7, was the son of immigrants and a three-term governor of a Northeastern state.

"When he ran against (President) Herbert Hoover in 1928 they even called him a liberal," Dukakis said, drawing out the last word like Bush does, as if it should be feared.

"Now before the vice president says it, I know I'm no Al Smith," he quipped, parodying the "you're no Jack Kennedy" line his own running mate, Texas Sen. Lloyd Bentsen, used against Bush's ticket partner, Indiana Sen. Dan Quayle.

But Dukakis used biting humor when he apologized that his wife, Kitty, could not attend because she was campaigning in Texas, Bush's adopted home.

"Kitty's in a hotel room in Texas right now, so I guess she qualifies as a Texan," he jibed, drawing applause and a smattering of hisses from the crowd.

"I like this a lot better than those crazy debates," Bush began after his opponent sat down. The Republican, who won a louder ovation than Dukakis from the well-heeled audience, tried to take charge by matching his rival's wit.

He blundered at one point by referring to a fellow GOP politician on the six-tiered dais, New York Sen. Alfonse D'Amato, as "Governor D'Amato." But otherwise it was smooth sailing as he mocked his blue-blood Yankee roots.

"I haven't seen so many people so well dressed since I went to a come-as-you-are party at Kennebunkport," he cracked, referring to his grand vacation home in Maine.

Bush said he was practicing his punch lines with his wife, Barbara, when he began to think he was sounding more like television's Johnny Carson.> "She looked at me," he recalled, "and said, `George, I know Johnny Carson. Johnny Carson is a friend of mine. And George, you're no Johnny Carson!"