Two days ago, C.A. Porter Hopkins was running in a neck-and-neck race with former Rep. Robert E. Bauman, both men chasing the GOP congressional nomination in Maryland's 1st District. The biggest issue was Bauman himself--his admission two years ago to problems of homosexuality and alcoholism and the question of whether he belonged back in Congress.

Now all that has changed. With Bauman's surprise exit from the race Thursday, people are turning their attention to Hopkins, a wealthy gentleman farmer, a one-time state senator, a staunch conservative and a politician accused by Bauman of "virulent and scurrilous personal attacks."

While Bauman supporters insist that Hopkins, with his gruff, blunt manner, was running a "smear campaign," those who know Hopkins insist that he is a "sensitive man" incapable of such tactics and aware that he didn't need to use them against Bauman. Yet such conflicting interpretations of Hopkins' political life are understandable for a man who is equally at home plowing his Dorchester County farm or quoting Thoreau to reporters, a man whose closest friends in the legislature included a studious Harvard-educated lawyer and a pugnacious Baltimore city restaurateur.

Still, there are a few things on which most people agree. "His overriding quality is fierce independence," said Jervis Finney, a former U.S. attorney in Maryland who grew up with Hopkins and served with him in the legislature. "He will do what he believes is right irrespective of party, pressure, pleading or whatever."

Many also say that ideologically, Hopkins and Bauman are much alike, conservatives who would be comfortable supporting the Reagan administration, but that stylistically the two men are worlds apart.

"Bob Bauman was a good congressman, voting the way the district would have wanted him to, and Porter would do the same," said Paul Nichols, a businessman in the small town of Hurlock who escorted Hopkins on a campaign tour last week. "But personally, well, you'd never see Bauman out here on the farm just talking to people. Porter is comfortable with that, he's a farmer himself."

Indeed, on a campaign trip that took him from the farms of the Eastern Shore to the fairgrounds at the northern tip of Maryland, Hopkins seemed to be all things to all people. With Robert O. Whiteley, the owner of a Hurlock pickle plant who dabbles in horseracing as a hobby, Hopkins talked business and thoroughbreds. When he stopped at Russell Stevens' big produce farm he discussed how the soil there differed from his own farm. And at the Cecil County Fair, he chatted with a gunsmith about the weapons he uses for duck hunting, one of Hopkins' favorite pasttimes.

One Republican was surprised by his campaigning ease. "My impression was that he comes across a tad too well bred, an arrogant child of the silver spoon," he said. But another observer of GOP politics, who at one time agreed with that view, said "Hopkins has changed 180 degrees. People find him likable and very serious about representing the 1st District."

That district had elected Republicans for two decades before Bauman's loss in 1980 to Democrat Roy Dyson, and Hopkins has said that now more than ever, "when the country has turned to the right and repudiated the 40-year drift to Democratic spending and near bankruptcy," the district should again be represented by a conservative and a Republican.

One of his political heroes is Sen. Barry Goldwater (R-Ariz.), who he thinks exemplifies "the best in American political experience" and whose views, he believes, are embodied in the Reagan administration. Hopkins agrees with Reagan's fiscal and defense policies, but as a "conservationist" who belongs to many wildlife groups and has worked to preserve the Chesapeake Bay, he is uncomfortable with some of the administration's environmental policies.

With Bauman out, Hopkins' remaining opponent in the primary is Russell Levin, a politically unknown Waldorf businessman, so Hopkins is turning his attention on incumbent Dyson. "He got in with a certain amount of luck," said Hopkins, referring to Dyson's victory after the disclosures about Bauman's troubled personal life. "And in two years he hasn't gotten ahold of anything substantive."

Dyson says he has snared a number of military appropriations for Maryland from his seat on the Armed Services Committee. He adds that he has used to Maryland's advantage the bargaining power he gained as a Democrat who has sometimes helped the Reagan administration. "That isn't luck," he said. "It's hard work."

Yesterday, as Hopkins campaigned in Ocean City, Bauman said he had made appointments to talk with federal and local prosecutors about his allegations that Hopkins' aides had threatened to use disclosures about his personal life in the campaign if he didn't withdraw. Hopkins has branded the allegations "ridiculous" and predicted authorities "will dismiss them as frivolous."

During a campaign break, Hopkins said he was certain he could heal any Republican Party wounds caused by Bauman's charges. Still, the candidate couldn't resist one final swipe at his former adversary. "A lot of elected Republicans are delighted Bauman withdrew ," Hopkins said. "They're saying, 'We're sure glad we won't have to run with him at the top of the ticket.' "