When Frankin Roosevelt came to power on a blustery March day almost half a century ago, Edmund Wilson, the great literary critic, was standing in the inaugural throng massed before the steps of the Capitol. He thought he had seen the makings of a dictator, Wilson wrote later. At the least he was certain he had witnessed the beginnings of dramatic changes in national life.

The analogy between then and now is hardly accurate, but Washington this weekend stands as city with a sense of great impending change, of crises unresolved, governental economic political, and of uncertainty if not forboding about the future.

A vignette: last week the president sent his top economic policy makers to Capitol Hill to brief the Republican congressional leaders privately. The president's people made their pitch: help them in ways to balance the budget, advise them on what and how to cut. One of the congressmen present found himself thinking, as he recalled afterward: "Here it is March 10 and the same people who sent up their budget a few weeks ago are back desperately asking for ways to change it. And I kept asking myself, 'What in the name of God has happened in 30 days to make them change so drastically. Inflation has been going up steadily all along, the same problems have been there before us all along, but here they are doing a complete turnabout. The only thing I can conclude is that they're reacting to what seems almost panic among the financial markets, a feeling that things are out of control and getting worse.'"

Whether the economic steps now being proposed will have the desired effects are unknown. But for the first time in more than a decade -- and in only a few other occasions since the birth of the New Deal and the modern era of big government emanating from Washington -- serious bipartisan efforts are being made to balance the budget, end deficit spending, and change the direction of the federal government.

While that significant aspect of governance unfolds in Washington, another kind of change appears at work in the country. It concerns politics, the state of the national parties, and the presidential prospect before us. At this point the most likely Democratic and Republican presidential nominees are Jimmy Carter and Ronald Reagan. Yet it becomes increasingly evident that strong sentiment exists nationally for an alternative.

The 1980 presidential year offers best opportunity, based on the widest spectrum of public opinion, for a different presidential candidacy in the fall. sIt's even possible -- albeit admittedly highly remote -- that an independent effort could actually win the White House. Should that occur American politics would be as altered as the coming of FDR and the New Deal two generations ago.

The arithmetic that Gerald Ford faced when he bounced into Washington last week, full of self-confidence and obviously eager to enter the lists was disheartening. It signalled that by only mid-March the GOP contest become extremely difficult, if not impossible, for a new contender.

If Ford had announced his candidacy immediately, he would have been able to qualify at best for only 12 primaries holding a total of 572 convention delegates. Two of the 10 largest states needed for victory -- Massachussets asnd Florida -- have held their primaries. He'd already forfeited a chance to compete in four of the other crucial big states -- Illinois, New York, Pennsylvania and Texas. Those alone hold 388 delegates. You need 998 to win nomination. His hopes rested on running strongly in four remaining major states, Ohio, Michigan, New Jersey and California. They contain 393 delegates, with California's 168, the richest of all political prizes, being the only big winner-take-all primary. It is, of course, Reagan's home turf.

With Reagan now holding 167 delegates and running nearly 4-to-1 over his opponents to date, he's virtually certain to go to Detroit next summer in the dominant convention position. A Ford candidacy further dividing the Reagan challenges would probably only have strengthened the Californian's position.

As George Bush fades, it appears only John Anderson remains. If you watched the Illinois debate the other night between Anderson and his fellow Republicans, two dominant impressions emerged: the continuing narrowness of the GOP and the strong opposition to a candidate like Anderson.

That leaves the fall.

Americans are increasingly independent and vote less and less for party labels in presidential elections. Some 160 million citizens conceivably could vote for president in 1980, and that figure includes the greatest number of potential young voters in our history; the postwar baby boom has come to maturity. They are the stuff of which an Anderson-type independent national candidacy can be made. That young Americans have not voted in major numbers in the past doesn't mean they never will. Anderson already has demonstrated an appeal to them, and to the large number of independents who do participate actively nationally.

But two problems confront that third-party alternative. They're major. Recent political "reforms" of the way money flows in politics have had the effect of limiting the race to the two major parties. This year the Democrats and Republicans will divide $40 million in public funds for their presidential nominees. Third-party candidates get nothing from the federal treasury. And a number of states have enacted stringent laws to keep other than traditional party presidential candidates off their ballots. The New York Times, in a careful study of state laws, estimated the other day that a Republican like Anderson who delayed an independent candidacy until after the convention would be unable to qualify for the ballot in 17 states, including four of the largest. And at most an independent candidate could get on only 33 state ballots and compete for 341 out of the total 538 electoral votes.

It takse 270 electoral votes to become president. Admittedly, the third party route is extremely difficult. Except for this: public discontent over the political choices rises in almost geometric proportions as the evidence of the failures of both parties accomulates. Not in 20 years of reporting has this observer encountered so many people seriously thinking of alternative political action. That doesn't mean it will happen.It means it might.