Washington — That scratching noise you hear may be the sound of people writing checks payable to the Republican Party. While Democratic money pours into the bitter and costly Hart-Mondale battle, the GOP is biding its time and amassing a huge bank account. Republican Party campaign committees raised $42 million during the first quarter of this year, according to recently released Federal Election Commission records. Democratic counterparts, by contrast, gathered in $7.3 million.
''Fund raising is going tremendously well,'' says Frank Fahrenkopf, Republican National Committee chairman.
In politics, as in life, money isn't everything. If it were, John Connally - business's first choice among GOP candidates in 1980, a man on whom political-action committee money fell like rain - would be president today. The Democrats wouldn't control the House of Representatives.
The two major presidential candidates, when it comes to funds for the general election, will be in essence stock-car racers driving identical sedans. Each will wage his general election campaign with a public grant of about $40 million.
But the Republicans' cash reserves, say experts, will give the party real advantages in the fall elections:
1. They'll be able to shower funds on GOP candidates for Congress.
Federal law limits the money that parties can contribute directly to adherents running for the House and Senate. But Republicans - who spend a lot of time ''finding ways to spend more than limits allow,'' according to one academician - have in the last four years discovered other ways to pump cash into congressional campaigns.
Through adroit use of state parties and ''coordinated expenditures,'' the GOP can now pay some 25 percent of the costs most House candidates incur, estimates Gary Jacobson, a political science professor at the University of California, San Diego. For those running for the Senate, the party can pick up a slightly larger part of the tab.
In 1982 the Republican Party spent some $12 million on congressional races, and will likely spend much more than that this year. The Democrats, of course, could do the same thing - but they just don't have the cash. In '82, the Democratic Party channeled only $3 million to congressional contests.
2. They'll be able to supercharge President Reagan's reelection campaign.
True, taxpayers foot the bill for most of the general presidential election. But the parties are allowed to augment their $40 million federal grant with a few million dollars of their own mad money.
The limit in 1984 is $6.5 million. The Republicans have already raised most of this, thanks to a $1,500-a-plate fund-raiser May 10 that featured lamb mignon in sorrel sauce.
The Democrats, on the other hand, never did scrape together all of this donation in 1980 (''We didn't even come close,'' admits one Democratic party official), and may not make it this year, either.
3. Republicans will be able to flood the country with buttons, posters, and other ''grass roots'' political paraphernalia.
Much of the money for this ''grass roots'' activity comes from national headquarters. It benefits Republican candidates across the board - ''from President Reagan down to John Jones, who's running for sheriff,'' says John Buckley, deputy press secretary for Reagan/Bush '84.
State and local branches of the Republican Party spent $15 million on grass-roots activisim in 1980, estimates Herbert Alexander, a political science professor at the University of Southern California. Democrats, for their part, spent about $4 million on the same thing.
So far, 1984 has proved a particularly bad year for Democratic Party fund raising.
Millions of loose Democratic dollars are being sucked into the vortex of the Gary Hart-Walter Mondale battle. Party officials are finding it hard to set up fund-raising dinners, for instance, because one of the presidential candidates has invariably just swept through the city in question.
''Things have gotten even more difficult in the last month and a half,'' says Floyd Fithian, finance director of the Democratic Senatorial Campaign Committee (USCD).
To make things worse, the Democratic National Committee must still make loan payments on $4.7 million it borrowed to produce a telethon last year. Democrats had hoped the show would net $20 million, but it proved a bigger flop than NBC's fall schedule.
And the Democratic fund-raising machinery, while improving rapidly, is just not the equal of the GOP's state-of-the-art equipment. The Democrats' direct-mail list, for instance, includes the names of 400,000 proven contributors. The GOP direct-mail program can count on 1.7 million donors, who each receive about 9 letters a year.
It is still an open question as to whether the Republican Party's cash is helping elect more Republicans. Political scientists, such as UCSD's Gary Jacobson, say money probably cut Republican losses in the 1982 midterm elections , but that it isn't clear by how much.
Democrats say their relative poverty just means they must focus cash on contests where it can do the most good. Mr. Fithian says his senatorial committee will channel money into 15 of this fall's 33 Senate races.
''In those 15, we plan to make a difference,'' he says.