First, some personal truth-in- packaging: An invitation to give my opinions on national politics to 140 members of the House Democratic Caucus here proved as irresistible as had a bid last December for a similar appearance in Annapolis before the Republican Senate Campaign Committee. And while the healing mineral baths on which this resort was built were unable to rival Lourdes' with a cure for all that ails the party, the retreat could turn out to help the Democrats become competitive once again in national politics.

In the view of caucus chairman and retreat organizer, Rep. Richard Gephardt of Missouri, House Democrats cannot continue "to act like independent contractors," indifferent to what the national party puts in itsplatform, or to whom it puts on its national ticket.

That same "independent contractor" mentality has been encouraged by both recent political history and the popularity of the jet airplane. Recent political history, especially Vietnam and Watergate and the anti-politics sentiment they fostered, has given us the incumbent congressman who reminds his constituents not of his legislative achievements in Washington but, instead, of how much of an anti-political maverick he really is and how much more he prefers to be back home in the district than on Embassy Row.

The jet sentences the member to proving his preference for the home town folk by coming home every weekend. Contemporary House members seem to concentrate their energy and attention outside Congress, the direct opposite of their predecessors, who came to Washington and frequently stayed for an entire session and got to know their colleagues personally. Before last weekend's retreat, a lot of House Democrats had never exchanged more than a few words with each other. In three days, many of them, and their families, got to know each other, which can only aid the cause of future party unity.

Recent political history has also meant that in order to survive in public office, Democratic House candidates have been required to emphasize the philosophical differences between themselves and their party's presidential nominees. For the last 17 years, those Democratic nominees have been a threat to other Democrats' elections. The last five Democratic presidential tickets, in the aggregate, carried fewer states -- 31 -- than Richard Nixon, with just 43 percent of the vote, won in the single election of 1968.

Bad news came to the Democrats in the form of numbers. According to current estimates, the 1990 census will show population shifts in the nation that will result in the pro-Republican Sun Belt gaining 19 more House seats (and electoral votes) at the expense of the more pro-Democratic Snow Belt. When Jack Kennedy carried Pennsylvania and Richard Nixon carried California, each state had 32 electoral votes. In 1992, it is predicted, California will have 50 electoral votes and Pennsylvania will be down to just 22. To survive, Democrats will have to become politically competitive in the South and the West.

It may have been in appreciation of this imperative that inspired Rep. Bill Hefner (D-N.C.), the shrewd emcee, to conclude the Saturday night sing-a- long from verses from each side's anthem in the War Between the States -- "Dixie" and "The Battle Hymn of the Republic."

Chrysler president and best-selling author, Lee Iacocca, was at the retreat and being eyed by a few victory- hungry Democrats in much the same way that Republicans, before 1952, must have covetously looked at Gen. Eisenhower: the successful, non-political, American "hero" who would be able to submerge and overcome the party's serious ideological problems with the electorate.

The caucus members were told that voters have grave doubts about the party's commitment to a strong national defense, because of Democrats' almost uninterrupted opposition to any proposed weapon since the invention of the Jeep. If Democrats think that characterization unfair, then they may remember that Ronald Reagan, who all the time insisted he rooted for Joe Louis and cheered for Jackie Robinson, opposed every major civil rights act of the '60s. Was Reagan's sincerity on civil rights ever questioned? You bet it was.

The Democratic Party did not achieve greatness or earn the nation's gratitude by asserting each American's categorical and unfettered right to feel good about himself and to remain in permanent touch with his feelings without any interruption from a nagging conscience. Leadership is not a search for the next level of personal liberation at home and further immunity from any responsibility abroad.

While the Republicas have become compulsive and promiscuous line- drawers (almost always with other people's kids), the Democrats seemed unwilling even to pick up the chalk. Until they agree upon and can articulate their definition of the national interest and what they propose to do to protect it, in a dangerous world, the Democrats will be unable to exploit the semi-felonious hypocrisy of an opposition that has stood for a doubling of the defense budget and a cutting of taxes, not to mention a balanced budget amendment, which would have made both actions illegal and impossible.

In all last weekend was a plus for the Democrats.