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How much do next month's elections for the U.S. House and Senate really matter? If merely asking the question sounds like a betrayal of civic duty, it shouldn't. The cliché is that the next race is always "the most important election of our lifetimes." But some elections have more far-reaching consequences than others.

The midterm elections in 2018 had high turnout. Emotions ran high concerning President Donald Trump and recently confirmed Justice Brett Kavanaugh. But while the results affected court appointments and symbolic impeachments, they had little effect on legislative outcomes. With Trump in the White House but his party uninterested in passing major legislation, the range of potential policies that could realistically be pursued was narrow. As it turned out, Democrats won the House but not the Senate.

This time, though, the stakes are relatively high — because the Democrats have both grand legislative ambitions and possession of the White House.

As of this writing, the Democrats seem likely to expand their majority in the Senate, according to FiveThirtyEight.com, but the Republicans have a 33% chance of taking control of it. The Republicans have a 69% chance of winning the House.

So it's plausible that in January 2023 America will have divided government. But it's also plausible that Democrats will be running Congress without having to depend as much as they currently do on Sens. Joe Manchin of West Virginia and Kyrsten Sinema of Arizona.

If the Republicans take the House, it is likely that almost every remaining Democratic legislative priority will die. But if Democrats keep the House and win a larger Senate majority — even a 52-seat majority, which would still be narrow by historical standards — all kinds of opportunities open up to progressives.

Nearly all Democrats support ending the filibuster, at least to enact legislation requiring all states to adopt their preferred policies on abortion and voting procedures. It is rumored that some Senate Democrats other than Manchin and Sinema have quiet reservations about this idea. But if they are too scared to voice these objections in public now, they might also be too scared to act on them if it came to a vote.

And Democrats, if this scenario came to pass, would be emboldened by a rare midterm victory. It is likely that both the abortion and voting bills would be enacted. Abortion would be legal nationally even in the third trimester if a doctor, nurse or midwife considered it beneficial for mental health. State parental-consent laws on abortion would be overruled. The Democrats might even have the votes for Medicaid funding of abortion. And states would be blocked from requiring photo identification in federal elections.

If the filibuster disappears for those two issues, it will probably disappear altogether. Pressure from inside the Democratic coalition would help to ensure as much. Union organizers, for example, would say changes to labor law are crucial to democracy and human rights, just like voting rights and reproductive rights. Why should their legislation have to overcome a filibuster?

Some Democrats are counting on this dynamic. Sen. Elizabeth Warren of Massachusetts recently told my National Review colleague John McCormack that a few more Democratic senators would put much of her wish list within reach, including child-care subsidies, increased regulation on guns and a wealth tax.

If, on the other hand, Republicans do well, winning a strong majority in the House and a narrow one in the Senate, they will not be able to enact changes of similar scope. That's mostly because President Joe Biden will still have a veto, but also because more Republicans than Democrats want to keep the filibuster. There won't be a national ban on abortion, even one that goes into effect after the first 15 weeks of pregnancy. Photo ID requirements won't be imposed nationwide. Taxes might actually go up a bit, depending on negotiations over tax cuts that are set to expire.

Because the party out of the White House usually does well in the midterm elections, coverage of the races this year has focused on whether Republicans will win in a "wave" or just a ripple. But there's a greater chance of liberal policy breakthroughs than conservative ones in Washington next year. That's what makes this election consequential, if not the most important of our lifetimes. Liberals have more to gain — and conservatives, more to fear.

Ramesh Ponnuru is the editor of National Review and a fellow at the American Enterprise Institute.