Two southern Democratic senators flew down to a beach hotel in Puerto Rico last month and came back with about $75,000 for the Democratic Party.

Why would a poor commonwealth with less than half the per capita income of Mississippi donate that kind of money when its people don't even have a voting representative in Congress? Because if Puerto Ricans can't influence Congress with votes, they can still win friends and influence people on Capitol Hill with money.

The Caribbean commonwealth is teeming with political party animals who know how to wine and dine Washington when there is something they want. And the influential politicos who hosted the Democratic fund-raiser want to derail the popular Puerto Rican movement toward statehood.

The quickie fund-raiser for the Democratic Senatorial Campaign Committee was held at the Dorado Beach Hotel outside San Juan. Sens. John Breaux (La.) and Bob Graham (Fla.) were the guests from across the water. Puerto Rican business owners and other locals paid $500 each to schmooze with them at cocktails and $2,000 to eat with them.

Miguel Lausell, the national committeeman for the Puerto Rican Democratic Party who organized the festivities, said the fund-raiser had nothing to do with the statehood issue now pending before Congress. Lausell is a friend and former cabinet member of Puerto Rican Gov. Rafael Hernandez Colon, an opponent of statehood.

Sources in the statehood movement told us that they also offered to host the fund-raiser for the Democrats, but could not guarantee as big a take as those who oppose statehood.

The tug-of-war to win congressional affection comes as Congress is drafting ballot questions for Puerto Ricans to choose among in a 1991 plebiscite. Their choices will be for independence, statehood or a continued commonwealth relationship with the United States.

The independence option has few followers in Puerto Rico, and the battle is between statehood and the status quo. Recent polls indicate that those who want Puerto Rico to be the 51st state have the edge. But they also have the smaller campaign war chest. Under the status quo, Puerto Rico is a tax haven for U.S. businesses that want it to stay that way and are putting their money into the commonwealth campaign.

The commonwealth movement is throwing money at some of the most skilled lobbyists in Washington as the House and Senate consider whether to authorize the plebiscite. Sources on the House insular and international affairs subcommittee, which drafted the ground rules, report being badgered by at least 35 lobbyists.

The annual celebration of Puerto Rico's Commonwealth Day on July 25 in Washington was billed as a non-political event. But the featured entertainer, singer Jose Feliciano, scolded statehood supporters for their lack of patriotism.

Statehood supporters have alleged that Colon is dipping into public money to pay for the lobbying effort. The General Accounting Office investigated the commonwealth's lobbying budget and other matters, but issued no report.