With four weeks remaining before the midterm elections, two facts sit side by side, and each party would prefer that you look at only one of them.

The first belongs to the Democrats. In the polling averages compiled at the end of September, they led the national congressional vote by a little more than eight points, roughly 50 percent to 42. A lead of that size, if it holds, is the kind that changes control of the House.

The second belongs to the Republicans. The Senate is not a national contest. Thirty-five seats are on the ballot on November 3. Republicans hold 53 seats to the Democrats' 47, counting two independents who vote with them, so Democrats must gain a net of four. The seats in play are, on balance, on ground that favors Republicans.

One would expect the professional forecasters to have reconciled those two facts by now. They have not. In ratings published within a day of one another in late September, the Cook Political Report counted seven Senate races as tossups. Sabato's Crystal Ball counted five. Nate Silver's model counted one, and placed Democrats at 52 seats. These are serious people working from much the same polling, and they differ by six races on the simple question of which contests are in doubt.

I mention this because the coverage of the next four weeks will be dominated by forecasts, delivered with decimal points. The decimal points imply a precision that the forecasters' own disagreement does not support.

What can be said with more confidence is that Republicans have made their task harder without help from anyone. Two sitting Republican senators, Bill Cassidy of Louisiana and John Cornyn of Texas, were denied renomination by their own voters. Texas, which has not elected a Democrat to the Senate since 1988, is now a contest between Ken Paxton and James Talarico that analysts rate somewhere between even and leaning Democratic. Seven Republican senators chose to retire, among them Mitch McConnell. Open seats in Iowa and North Carolina that an incumbent might have held are now competitive.

A party that removes its own incumbents in a difficult year is expressing a preference, and it is entitled to do so. It should not then be surprised by the bill.

Democrats have their own exposure. They are defending open seats in Michigan and New Hampshire, and some polls in New Hampshire show a dead heat. A net gain of four requires winning nearly everything within reach while losing nothing.

Then there is the matter no campaign controls. Brent crude was trading above $101 a barrel this week as attacks on tankers in the Strait of Hormuz increased, and the White House is reported to be examining ways to bring fuel prices down before Election Day. Voters have punished presidents for the price of gasoline for half a century, fairly or not.

My counsel to the reader is modest. Treat any forecast as a description of what is known today. Notice which facts each side leaves out. The count on November 3 is the only number that will matter.