The ballot measure next month proposes to nudge the District of Columbia toward statehood could become either a shortcut or a long way around for full home rule in the nation's capital.

If D.C. voters approve the statehood initiative that will appear on the Nov. 4 presidential election ballot, it will set in motion a complex and controversial process without direct precedent in United States history.

But if a potential constitutional dispute is averted, there is little doubt that Congress has power -- by simple majority vote in both houses -- to admit the District of Columbia as the nation's 51st and only totally urbanized state.

In land area, the city's 67 square miles makes it only 1/15th the size of Rhode Island, now the smallest state in area. Using 1970 census data, the District of Columbia has more people than seven existing states.

The statehood idea is being pushed by an ad hoc group calling itself the Statehood Initiative Committee. Headed by John E. (Ed) Guinan, a civic activist, the group last winter collected 21,771 signatures on petitions -- 17,281 of them declared legally valid -- more than enough to lead the D.C. Board of Elections and Ethics to put the issue on the ballot. However, the committee had to go to court to force the board to act.

Guinan said the statehood coalition that sponsored the measure plans to spend an overall total of about $25,000 to try to win approval for the measure. He said about $15,000 of that amount already has been spent collecting signatures natures to get the referendum on the ballot, and for paying the court costs when the D.C. Board of Elections and Ethics initially tried to keep it off the ballot.

Guinan said his group has registered about 8,000 new voters in the last year, and he said that the statehood coalition is looking for its victory margin east of the Anacostia River, where volunteers are trying to mobilize people who do not traditionally vote. The campaign will buy some radio advertisements and will distribute about 150,000 four-page tabloids explaining the initiative.

Guinan also is busy picking up prominent supporters. Last Thursday night, the measure was endorsed by the city's Democratic State Committee, and the list of supporters reads like a who's who of prominent elected District officials.

The one notable exception is D.C. Del. Walter E. Fauntroy, who is leading the strongest challenge to the initiative. Fauntroy opposes the measure, according to an aide, Johnny Barnes, because the referendum's timing comes when some states are considering the constitutional amendment to give the District of Columbia full voting rights in Congress. Barnes also said the language of the proposal is severely flawed and never has had sufficient public discussion. "It's almost as though it's been railroaded through," Barnes said.

Only by statehood, the promoters contend, can Washingtonians gain full legislative, judicial and budgetary self-determination along with representation in Congress. They contend the city's present limited home rule is a sham.

Since the statehood idea never has been tested by D.C. voters or by Congress, the real prospects for statehood are anybody's guess at this time. Both the voters and national lawmakers may have two chances to pass upon the issue.

There is little in American history to suggest how long Washington's journey to statehood might take.

At the speedy historic extreme, Texas became a state instantaneously when Congress voted in 1846 to annex the former Mexican province as American territory. It took neighboring New Mexico 62 years, from its application in 1850 to admission in 1912, to achieve statehood.

The District of Columbia's route would be circuitous:

First would come the November vote, Initiative Measure 3 on the ballot, asking D.C. voters whether they want to call a convention at which elected delegates would draft a proposed state constitution.

If the initiative is approved by a majority of voters, Congress would have 30 legislative days in which to review the proposal. It could let the proposal go forward or it could kill it by resolution of disapproval.

If Congress lets the proposal stand, District of Columbia voters would elect 45 delegates to the constitutional convention. Of these, five would come from each of the city's eight voting wards, and another five would be elected city-wide.

The convention would draft the proposed constitution, deciding upon such things as the state's name -- perhaps Columbia -- along with such matters as the makeup of its legislature, the term and powers of its governor and financial relationships, if any, with the federal government.

Another election would be held, giving voters the right to ratify or reject the constitution. At the same election, voters would choose congressional representatives: two U.S. senators and, given the decline in D.C. population in the past 10 years, probably one House member.

If the voters ratify the constitution, application would be made to Congress to admit the new state. As with all 37 states admitted since the original 13 colonies formed the union, a simple majority in both houses is sufficient.

The president would sign or veto the admission bill. If it becomes law, the District of Columbia would join the union and its members of Congress would be seated.

The most recent states to follow a similar course were Alaska and Hawaii, both admitted in 1959.

The District's application would be precedent-setting in one respect. It could be the only "federal district," with a unique form of government provided under a special clause in the Constitution, to seek statehood.

According to a Congressional Research Service report, there were two main ways existing states were added to the original union. Twenty states were carved from American-controlled land and admitted without ever being organized governmentally as territories. Thirteen states passed through territorial status.

Another four states were sliced off from territory of existing states -- two of them, Kentucky and West Virginia, from Virginia. Texas and California, special cases, were hastily admitted after U.S. settlers and armed forces seized them from Mexico.

Another Congressional Research Service report, prepared in 1977, raised one potential and highly legalistic constitutional roadblock to D.C. statehood.

It suggested that the issue, if raised during deliberations, might have to be settled in court.

Simply stated, here is the issue:

The Constitution says that a new state can be created from the territory of an existing state only with the permission of the existing state. Maryland ceded jurisdiction over all the land on which the District of Columbia now is located to the U.S. government to servesolely as the national capital. Therefore, Maryland -- the theory goes -- may have standing to block District statehood.

But D.C. statehood advocates scoff at the idea that such a challenge might be valid.