Both in the Washington and in his adopted Minnesota home, the death of Sen. Hubert Horatio Humphrey leaves a political hole as wide and deep as the endless interests that made him as important figure across the full breadth of the legislative spectrum.

Humphrey's long bout with cancer apparently did little to lessen the catholic range of his concerns. As late as Wednesday, two days before he succumbed to his disease, he was on the telephone working out details of one of his major pieces of unfinished business, a rewrite of U.S. foreign aid legislation.

At about the same time, his staff was busy rounding up co-sponsors for his major pending domestic initative, the revised Humphrey-Hawkins employment bill.

Those bills are cited by Capitol Hill sources as the pieced of import legislation most likely to be affected by Humphrey's passing.

Their courses will be more shaken than the inner workings of Minnesota's Democratic-Farmer Labor Party (DFL), and entity unique in American politics, fused from separate Democrate and Farmer-Labor Parties at a convention chaired by Humphrey in 1944.

Humphrey's death is expected to touch off a political scramble in a state already once shaken by former Gov. Wendell R. Anderson's arranging to have himself appointed to the Senate vacated last year by Vice President Mondale.

The current governor, Domocrat Rudolph G. (Rudy) Perpich, has flatly stated that he is not interested in Humphrey's seat. He has indicated that he will probably appoint a caretaker - a person who will not seek election to the vacant seat - to serve until a special election can be held.

Leaders of the DFL said yesterday they will probably push a bill that would schedule a special election for the balance of Humphrey's term, which ends in 1980, to coincide with the November election this year.

Thus Minnesota voters will face the unfamiliar task of electing two U.S. senators in November. In addition to the contest for Humphrey's seat, Anderson will be seeking election to Mondale's old shot.

Politicians who already have jobs in Washington will also be affected by Humphrey's passing. Humphrey chaired the Foreign Assistance Subcommittee of the Senate Foreign Agriculture, Nutrition and Forestry Committee.

The process of assigning new committee slots will be complicated for Senate Democratic leaders by the need to fill the Energy Committee vacancy created by the death Thursday of Sen. Lee Metcalf (D-Mont.).

Metcalf was a member of the energy conference committee that often split down the middle, 9 to 9, on major pieces of energy legislation. His death leaves another important vacancy to be covered in the shuffle of the Senate Democratic leadership.

It is unlikely that anyone will fully be able to fill the legislative vacuum Humphrey's death leaves. The foreign aid bill, the basis for most U.S. foreign assistance, was undergoing a major rewrite at the hands of Humphrey and Sen. Clifford P. Case (D-N.J.)

The purpose of the rewrite was to clean up the often barnacled language of the 200-page bill, and to pull most development efforts under one unbrella organization, which Humphrey intended to push for a Cabinet-level slot.

Humphrey's support was considered crucial to overcoming anticapated objections from the Agency for International Development.

Meanwhile, had his health held, Humphrey would likely have been a floor leader of the fight to approve the Panama Canal treaties. Several sources speculated that his death may have hurt, if only slightly, the treaties' chances of passage.

Humphrey also had been expected to be a moderaing force to hardlining Sen. Henry M. Jackson (D-Wash.), whenever the SALT II treaties come before the Senate for approval.

In the Agriculture committee, Humphrey would have led a fight for the expansion of a program of nutritional aid to women and young children, a program he shepherded into being in 1972. That bill comes up for reauthorization and new funding this year.

He was also involved in vocating urban and rural development banks.

Back in Minnesota, Democratic Reps. Donald M. Fraser and James LOberstar are leading contenders for Humphrey's Senate seat in the November election. A third possible candidate is Nicholas Coleman, leader of the state senate's DFL majority.

On the Republican side, the most likely candidates are Reps. Thomas M. Hagedorn, a farmer and conservative second-termer, and Bill Frenzel, a moderate who has represented a suburban Minneapolis district since 1971.

Not only politicians are effected by Humphrey's passing. The Minnesota Florist Association reported that state florists have received about 4,000 orders for flowers to be sent to the state capitol, where Humphrey's body will lie in state after it leaves Washington today.

There have been so many oders that the governor's office has set aside a large room to handle the overflow.