Outside the Always diner on Rte. 40 here, a large marquee proclaimed "Welcome Mike Barnes," while along the front of the diner Barnes' face smiled out from posters that were hanging close to the "No Shirt, No Shoes, No Service" sign.

Inside, four men in flannel shirts and caps shrugged and shook their heads when asked by a reporter if they knew who Mike Barnes is.

Few people looked up from their breakfast and none of the diners talked to Barnes as he entered for his news conference, the last in a statewide series to announce that the congressional representative from Montgomery County is seeking the Democratic nomination for the U.S. Senate.

"They've got a tough task ahead of them," said Arthur Katz, owner of the Always diner, as he shook his head and laughed.

Katz, an active member of the Democratic Party in western Maryland, said few people have heard of Mike Barnes in Hagerstown, although it is less than an hour's drive from Montgomery County.

This afternoon on the Eastern Shore, things were much the same. Standing on a brick walkway next to the White & Leonard office supply company in the shopping district of Salisbury, Barnes declared his candidacy to the half-dozen local reporters who appeared.

A short time later a gray-haired woman with glasses and a shopping bag walked by and stopped to inspect a campaign banner. "What's this?" she asked. A Barnes assistant enthusiastically told her, "That man's running for Senate."

"I'm Mike Barnes," he yelled out good-naturedly at the woman as she resumed walking. "Mike who?" she said quizzically.

"Mike Barnes," he repeated. "Oh, nice to meet you, Mike Barnes," she said politely, as she briskly walked out of yelling range.

At each stop across the state, local reporters hit Barnes with the same question: How can he win when few people in those areas know him?

Barnes readily acknowledges that if a poll were taken today, he would probably trail Gov. Harry Hughes and Rep. Barbara Mikulski, two other Democrats interested in the seat of retiring Republican Sen. Charles McC. Mathias Jr. But Barnes likes to point out that when he first won his 8th District congressional seat in 1978, he was an obscure underdog. He exudes the confidence of a man who has never been defeated.

Obscurity, said Barnes, is not an insurmountable hurdle. The key is money -- about $1 million to $1.5 million -- so he can blanket television and radio airwaves with advertising and households with mass mailings.

Barnes said he will spend the next two weeks on the phone trying to raise money, and he plans to hold fund-raising events in New York and other states.

Then, said Barnes, there is the free help from persons like a former Marine buddy, who is a conservative Eastern Shore Republican but who has promised to help. And there was the radio reporter who, after an interview, offered broadcasting tips -- suggesting that Barnes repeat his name in his comments, much as product names are repeated several times in 30-second radio commercials.

At this early stage in the campaign, Barnes is bubbling over with optimism, despite the odds. "Look here," he joked, pointing to his horoscope. "It says, 'Focus on hopes, wishes, dreams, new starts in new directions' . . . . It's a good omen."