NASHUA, N.H. — NOWADAYS, if you run for the Oval Office you've got to run hard. Consider a typical 24 hours in the itinerary of Republican presidential hopeful Arlen Specter: Illinois for breakfast and lunch on Friday. Cedar Rapids, Iowa, for dinner. Over to Des Moines for a Saturday morning TV show. On to Denver for a fund-raising lunch.
There's a reason they don't call it walking for president. ''I'm already tired,'' sighs the Pennsylvania senator's wife, listening to her husband recite his schedule.
Competing for a major party presidential nomination has always been a peripatetic exercise. But this time around, the pace for Republican candidates is particularly frenetic. The reason: the compression of next year's presidential primary schedule.
For the first time, almost all the major primaries will be over by the end of March. This speeded-up process has seriously changed tactics and strategy for all contenders. It could even have a radical impact on next year's presidential general election.
Among the effects observers point to:
*Candidates have had to announce and begin campaigning far sooner than before.
''President Clinton did not declare for the presidency until October 1991,'' says Sen. Richard Lugar of Indiana. ''Everybody in our race has declared by the end of April, except for Governor [Pete] Wilson [of California].'' Thus candidates are working with the same intensity in April and May this year that they were in October and November four years ago, he says.
*Candidates have had to expend much effort on raising large sums for their war chests long before the primaries start. Unlike past election cycles, there probably won't be enough time for money to flow in and bolster any candidate who does unexpectedly well in early contests. That's a pattern that Jimmy Carter, for one, followed to leap from relative unknown to nominee.
''What we lose here is the possibility that someone who does well in Iowa or New Hampshire and is at the back of the pack has enough momentum to raise money to keep going,'' says political analyst Stephen Hess at the Brookings Institution. Before, ''people who were not well known or rich could get a toehold. Now there is little possibility of that because of the financing.''
*The race will effectively be over by April 1. There will be approximately 50 primaries or state caucuses in the first three months of 1996. Some experts believe the GOP field will be winnowed to only two real contenders as early as the day after the New Hampshire primary.
All this seems to favor Sen. Bob Dole of Kansas, the front-runner for the Republican flag. The compression of the campaign season means that candidates who start off with name recognition and/or money are in much better shape, according to Hess and others. ''It becomes a case of whether the front-runner stumbles,'' he says.
The conventional wisdom among many observers is that the race is now Sen. Dole's to lose. He leads his rivals by wide margins in early polls. This state of affairs disturbs a lot of people, not least other candidates. ''The front-loading of the primary process is a disaster,'' says Rep. Robert Dornan of California. ''It makes the whole process an obsession with money and tin-cupping.''
Will all that money really be necessary? Experts say a candidate will need $20 million to make it through the primaries. Through March, GOP contenders together had spent almost $11 million. Sen. Phil Gramm of Texas spent $5 million, more than all the candidates did in the first three months of the 1988 race.
Not everyone agrees on the importance of money next year, however. ''I think that the money has been overemphasized,'' Senator Specter says. ''I think that ideas and leadership are a lot more important.''
Ronald Kaufman, former President Bush's political director, also dissents. ''This myth that you need $20 million may be just that.... Money may not be the be-all and end-all.''
He argues that there are too many primaries at once for $20 million or $30 million to buy enough television advertising to make a difference. Mr. Kaufman says that free media exposure will be much more important this time around -- and he doesn't just mean the television news. He points to the many places voters can now get information: more newspapers and TV networks covering the races, computer bulletin boards, and C-Span.
''Say a second-tier candidate overachieves in Iowa and New Hampshire and breaks out,'' Kaufman says. ''The huge amount of information available will more than take care of not having $20 million in the bank.''
The tight primary schedule is a big change from 1976, when Jimmy Carter won the Iowa caucuses, then the New Hampshire primary, and fought his way through a tough series of spring primaries. He locked up the nomination only after the California primary on June 8.
Hess says an early decision could increase the possibility of a third- or even fourth-party candidacy, if a large percentage of the public is unhappy with the outcome. Plenty of time will remain for a Ross Perot, Colin Powell, or other independent candidacies to get off the ground.
Bigger regional voice
The compressed schedule also reflects the fact that regionalization of primaries has intensified. This trend began in 1988, when a group of Southern states agreed to hold their ballots on ''Super Tuesday.'' The object was to increase Southern influence in the Democratic Party and help pick a moderate Democrat. Next year may see a New England regional primary March 5; the South's Super Tuesday will be March 12; and a Great Lakes primary from Pennsylvania to Wisconsin will be March 19. ''That's probably a useful development,'' Hess says. ''It promotes rational scheduling and advertising.''