In politics, just as in sports betting and record temperatures for this date, numbers do count. And The Gipper's stats are genuinely imposing. Of the nation's 435 congressional districts, 308 were carried in 1980 by Ronald Reagan, which looked impressive until last November, when, according to the National Journal, Reagan probably defeated Walter Mondale in 371 House districts.

But both victories appear to have been "lonely landslides" for the president, because in today's House of Representatives there are actually fewer Republican members than there were when Richard Nixon and Spiro Agnew were reluctantly leaving their high federal positions to return to the private sector.

Is the explanation simply, as some have concluded, that Democrats -- as the pro-politics and pro-government party -- have been able to recruit more interesting and electable House candidates? Or maybe it's that the undeserved elevation to civic sainthood of the unreflective (I vote for the man, not the party) ticket splitter has further shortened presidential coattails.

But beneath these superficially encouraging numbers for Democrats, there's a profoundly changed reality wrought by the Reagan landslides: While the Republicans have become much more of a unified national party, the Democrats have become much less of one.

Imagine yourself a Democratic House candidate in either of the last two presidential years. Regardless of the warmth of your personal feelings for Jimmy Carter or Fritz Mondale, you had to know that both men, and the party they led, constituted serious professional liabilities for you. You did not beg them to campaign in your district. If the nominee did show up in your home town, you adroitly schemed for the construction of a public platform wide enough that you could both be present on it and still be safely out of camera range.

Furthermore, the issues their candidacies raised -- double-digit inflation, Iran and promised tax increases -- were about as much help to your own campaign as an October summons to testify before a grand jury on public corruption. Your national party put you on the defensive where it's a lot tougher to win elections. In a country which 90 percent of its citizens believe to be "the very best place in the world to live," the national Democratic conventions seemed to turn into televised litanies of our national ills and shortcomings.

To survive, many Democratic House candidates emphasized their distance and their independence from the national platform. Republican candidates, understandably, did just the opposite, grasping for any public association with the Reagan magic.

Contrast the experiences of the 55 white Democratic congressmen most recently elected to the House with those of their Republican counterparts. Only five of those House Democrats represent a district carried by the Democratic presidential ticket. On the Republican side, the figures are more than reversed: of the 55 most recently elected GOP House members, every one comes from a district Ronald Reagan carried. And in the 17 House districts that switched from Democrat to Republican last November, the winning GOP House candidate averaged just 53 percent of the vote, while Ronald Reagan swept those districts with 66 percent of the total. That's a measurable difference.

As Republicans learned during the Roosevelt years, the national party can come to represent a threat to the individual officeholder struggling for political survival. The House Democrat of the '80s, faced with political Darwinism, runs mostly on his own, giving little attention and less support to what the national ticket happens to be emphasizing. If Mondale had been able to spring a historic upset, there would be today no Democratic consensus on national programs or priorities.

For House Democrats, a 1986 off- year race -- when their own party is responsible for neither the government nor the economy and when they can set the terms of the public debate in their own districts -- is a lot more appealing than is 1988, when the debate will be set by the national tickets. The Democrats control the House but not their own political destiny.