About the elections to the House, you can get widely different predictions. Rep. Guy VanderJagt (R-Mich.), head of the Republicans' campaign committee, thinks that as things stand today his party could gain 25 House seats and wrest working control of the chamber away from Speaker Tip O'Neill. Rep. Tony Coelho (D- Calif.), head of the Democrats' campaign committee, thinks his party could gain or, at worst, lose up to seven seats, leaving Mr. O'Neill in solid control.

There's support for both views when you look at the races district by district. The Democrats can cite polls showing almost all their incumbents well out in front, even in front of Republican challengers who've already spent more than $200,000. The Republicans reply that challengers usually make their charges in the last weeks, as they and their issues finally become well known; they say they have several dozen candidates in positions to win.

Both are talking with an eye on the PACs and other lobby-oriented money-givers headquartered mostly in Washington. On issues they generally prefer Republicans. But they want to stay chummy with the Democrats if they control the votes and committee posts that decide issues in the House. So for the next couple of weeks they'll be squeezed by both sides, and some of their decisions will hinge on how they think things will turn out. The Republican Party has done a brilliant job of raising money and aiding its candidates, and most Democratic incumbents are adroit fund-raisers. Even so, almost every candidate at this stage believes that an additional $50,000 can make all the difference.

Who's going to win? Don't assume that coattails automatically decide: voters have no mechanical difficulty splitting tickets, and Republicans got 192 House seats when Ronald Reagan won 51 percent of the vote and when Richard Nixon won 61 percent in 1972. The national ticket can make a difference in two ways: by affecting turnout and by championing ideas that will help its congressional ticketmates win. Mr. Reagan did that in 1980 by running on the same conspicuous platform -- lower taxes and a stronger defense -- as did Republican House candidates. That worked when both were running as challengers in a year when voters were dissatisfied with the status quo.

It's different this year. Voters satisfied with the status quo may decide to keep their incumbent Democratic congressman as well as the incumbent Republican president. Many may be wary of the additional spending cuts or tax changes they think an all-Republican government is likely to produce. Recent polls and election results suggest that voters want the policies that have resulted from the combined cooperation and conflict between the Republican administration and Senate and the Democratic House. If that's so, Mr. O'Neill's chances of being returned to power Nov. 6 may be nearly as good as Mr. Reagan's seem to be.