As Prince George's County Executive Winfield M. Kelly Jr., begins his bid for election against Republican challenger Lawrence J. Hogan, he finds himself in a paradoxical position:

On one hand, he is the head of the state's most powerful county organization, a political juggernaut that lost only seven of 86 local races in Tuesday's primary.

On the other hand, Kelly may be one of the organization's most vulnerable candidates in November.

As the general election race begins, even Kelly's own polls have shown him trailing Hogan, a former congressman - despite the Democrats' 3-to-1 registration edge among the county's voters.

Hogan also is taking heart from Tuesday's Democratic primary defeat of Acting Gov. Blair Lee III and his running mate Steny H. Hoyer, one of the original architects of the Prince George's organization.

The primary victory of Democrat Harry R. Hughes, Hogan said yesterday, "certainly indicates that a substantial number of Marylanders are against the machine."

"Winnie Kelly is now the last living remnant of the (Prince George's) machine and the handwritting is on the wall for him. His days are numbered," Hogan added.

The "last living remnant" line was a reference to Kelly's position as the remaining member of the one-time triumvirate that put the Prince George's organization together. Hoyer's defeat puts him out of the picture for the moment and party power broker Peter O'Malley is not ready to take an active role in the November campaigns.

Kelly, however, maintains that he will have little trouble winnig victory in November. "We're going to win," he told campaign workers Tuesday night.

"Hogan is popular and he's well known but we have momentum now, I can feel it."

Kelly also sloughed off the Lee Hoyer defeat as a factor in his race saying, "Both Blair (Lee) and Harry (hughes) are superb administrators. I'll work for Harry just as I would have worked for Blair. And I expect him to help me just like Blair would."

Both Kelly and Hogan said yesterday that Kelly's record would be the central issue in the race. "I'm just going to point very clearly to the major tax decline we've had here in the county, to the decline in the crime rate and to the progress we've made in the schools," Kelly said.

"His record will be the prime issue," Hogan said. "He's given us new, varied and higher taxes and he's gone to the legislature to gouge more money from the people time and again. And I'll be talking about the waste in county government which has gone on during his administration."

While Kelly would not classify himself as "the boss" of the county organization, he agreed yesterday that, "because of my office I am the titular head." He said he would ask Hoyer to work for him during the campaign but said the expected no help from O'Malley. "I'm sure Pete would tell you he's just not involved in local politics any more," he said.

The county executive race looks to be easily the most interesting race. Ten of the 11 Democratic organization candidates for County Council won nomination with only Kelly press aide John A. Lally failing to gain a spot on the November ticket.

Lally finished seventh in the atlarge race in which only the top six finishers advance. School board member Sue V. Mills, who rose to prominence in 1973 when she was an outspoken opponent of forced busing, was the "outsider," or anti-organization candidate who helped defeat Kelly by finishing fifth.

The Republicans had only 11 candidates running for the council, so all moved into the general election without opposition in the primary.

But it is the county executive race that the organization will be concentrating on. "Obviously that's the one we'll be working on hardest," campaign manager John McDonough said. "The state race shouldn't really affect our race even though Hughes is a surprise. In the end, this race will be decided on local issues, not what happens statewide."

Late returns in Prince George's yesterday showed Richard Anthony Blancato winning the Republican state Senate nomination in District 23, defeating Joseph A. Aukward. In District 28, Ray Velasquez defeated Theodore Hilgier for the Senate nomination, and Ella Ennis, James Panor and William Crandell won Repubican house of Delegates nominations.