At least 17 of the non-incumbents running for Congress this year worked for the executive branch at some time in their career.

Eleven men and two women are running as Republicans for House seats, and three men are running as Democrats. In addition, Jack Lousma, a former NASA astronaut, is running as a Republican for a Senate seat from Michigan.

One candidate is considered an almost sure bet to win: Fred J. Eckert (R), whom President Reagan named ambassador to Fiji in 1982. Eckert, a former state senator, is trying to succeed retiring Rep. Barber B. Conable Jr. (R) in New York's heavily Republican 30th District.

Candidates who are expected to run well include:

* Elise R.W. du Pont (R), a former assistant administrator of the Agency for International Development who is running for the House seat from Delaware.

* David A. Christian (R), a former Labor Department official who specialized in employment opportunities for veterans, running in Pennsylvania's 8th District.

* Helen Delich Bentley (R), 60, a former chairman of the Federal Maritime Commission, running in Maryland's Second District.

Other serious contenders include Republicans Michael Norton, a former regional administrator of the General Services Administration, in Colorado's 3rd District; Rob Quartel, who served in President Gerald R. Ford's White House, in Florida's 11th District; Lewis Crampton, a former Environmental Protection Agency official, in Massachusetts' 10th District; Joe Barton, who served as a White House fellow in the Energy Department, in Texas' 6th District; and Democrat John P. Flannery II, a former Justice Department prosecutor, in Virginia's 10th District.