In the vote, 206 Democrats rejected the President's $100 million proposal and only 46 supported him.
Among the most eloquent of the Democrats in raising the Vietnam specter was House Speaker Thomas P. O'Neill Jr.
In a final summing up for the opposition, moments before the vote, O'Neill said Reagan's program "takes us further down the road, further toward a situation where our country's troops will be involved, just as covert aid became overt aid; just as humanitarian aid has now become lethal; just as we have moved from the role of arms supplier to that of trainer and adviser.
"And I see that pattern continuing. I see us becoming engaged, step by step, in a military situation that brings our boys directly into the fighting."
When the debate opened Wednesday, O'Neill characterized the issue as "a Tonkin Gulf vote," a reference to a 1964 resolution successfully sought by Johnson which opened the door to direct American involvement in Vietnam.
Another who raised the Vietnam image was Rep. David Obey (D., Wis), who declared that Reagan threatened to put the United States "on the slippery slope to direct military involvement."
The Reagan White House and Republican congressional leaders strongly disputed these charges and argued that the administration's objectives were exactly the opposite.
Top administration leaders, including both Defense Secretary Caspar W. Weinberger and Secretary of State George P. Shultz, told congressional committees that the administration is supporting the contras precisely
because it wants to avoid the risk that American Marines might have to be sent to Central America some day.
The House Republican leader, Rep. Robert Michel of Illinois, declared with emotion that the "last thing we want" is "to commit our boys - our object is just the opposite."
There is a widespread feeling in Congress, in fact, that the climax of the battle in Congress over what to do about Nicaragua is still a year or two away. The logic of this judgment is that Reagan will do everything he can to try to bring down the Sandinistas in the next year or two, hoping that a combination of pressures will do the job.
If those pressures fail, however, he will be faced with a situation as he prepares to leave office that he has already declared he does not want.
"I have only three years left to serve my country," he said in his televised speech on Nicaragua last Sunday, "three years to carry out the responsibilities you have entrusted to me. . . . Could there be any greater tragedy than for us to sit back and permit this (Sandinista) cancer to spread, leaving my successor to face far more agonizing decisions in the years ahead?"
The President sounded like a man who did not intend to leave office while the Sandinistas are still in power in Nicaragua.
If it comes to that decision, many in Congress fear that Reagan may finally choose to send in the Marines or other U.S. combat forces.
And that apparently is why so many Democrats voted against him.