Presidental adviser Edwin Meese, trying to dispel impressions that the White House is not enthusiastic about the U.S. Senate campaign of Lawrence J. Hogan, declared last night that President Reagan and the Republican Party are "solidly and enthusiastically behind" the Maryland Republican.

Meese is the first high-ranking presidential surrogate to campaign for Hogan, who is challenging Sen. Paul S. Sarbanes (D).

The brief appearance by Meese at a Washington reception honoring Hogan was an effort to counter reports by some top GOP strategists that the White House would not give Hogan its full support.

Last week some Republican Party planners said that Reagan, who campaigned yesterday in Virginia for GOP Senate candidate Paul S. Trible, would not make a similar appearance on behalf of Hogan in Maryland.

"Tonight we're letting the people know that we're very interested in this race," Meese said to an assemblage of 75 people, including representatives of political action committees from Bechtel Corp., Goodyear, and Allied Corp. "We think this is a very important race, a very strategic race and we are enthusiastically, 100 percent supporting Larry Hogan."

Meese characterized as "flatly untrue" suggestions that the White House lacks enthusiasm for Hogan. But he was unable to say whether Reagan or Vice President Bush would actually come to the heavily Democratic working class state to campaign for the 53-year-old Prince George's County executive.

Although top GOP strategists have termed Hogan's race a long shot, Meese told the group of potential contributors that "the momentum was building for Larry Hogan" and that the White House hopes "the funds will flow."

Meese, who stayed at the reception about 20 minutes, did his best to lavish praise on Hogan, saying the candidate had "a rare combination" of talents that had won him election to three terms in Congress as well as county executive.

Meese left the reception after delivering brief remarks and posing for pictures with Hogan and Hogan's wife, Ilona. U.S. Transportation Secretary Drew Lewis, White House political operations director Ed Rollins and Sen. Bob Dole (R-Kan.), whose personal political action committee gave Hogan a check for $2,500, also attended the reception.

Sarbanes, so far, has built a war chest double the size of Hogan's.

Hogan is basing his ability to beat Sarbanes on a massive influx of contributions from around the state and the country.

Last month he traveled to Southern California and spoke to representatives of 40 political action committees belonging to various industries. He made a similar trip to Texas in July and received donations from a handful of conservative political action committees.

In order for his campaign to succeed, he said last night, he will require more contributions to stage a media blitz in the remaining four weeks of the campaign.

At last night's reception, prospective contributors were given copies of a personal letter signed by Reagan inviting them to help with contributions to Hogan's campaign.