ANALYSIS — The Democrats’ chances of netting at least two Senate seats always seemed like a long shot. But a month ago, the stars looked to be aligning for them. Today, those stars tell a different story.

With the Republican challenger, Rep. Kevin Cramer, opening up a clear lead over Democratic incumbent Heidi Heitkamp, the North Dakota Senate race looks all but over now, according to multiple insiders. That means Democrats will need to swipe at least three GOP seats to take back the Senate — an outcome that currently appears somewhere between unlikely and impossible.

Democratic prospects have also faded over the past couple of weeks in two important states, Tennessee and Arizona. And in Nevada, a state that went for Hillary Clinton two years ago, Republican incumbent Dean Heller is running even or slightly ahead of Democratic Rep. Jacky Rosen. In Texas, where Democratic enthusiasm for Rep. Beto O’Rourke’s Senate bid is off the charts, GOP incumbent Ted Cruz continues to hold a clear and consistent advantage, with no sign that Lone Star state voters are going to fire him.

To make matters worse for Democrats, Republicans continue to threaten their incumbents in Senate races in Missouri, Indiana, Florida and Montana. (Four other states that Donald Trump carried in 2016 — Michigan, Ohio, Pennsylvania and Wisconsin — are not competitive.)

The Democratic scenario for capturing the Senate always depended on swiping at least two — and probably three — Republican seats. That is now not happening.

It’s possible that events over the next few weeks will change that arithmetic, but for now, net gains for Senate Republicans seem more likely than Democratic ones.

This year’s Senate results are crucial, in part, because they will help determine the parties’ Senate prospects for the 2020 election. A GOP gain of two or three Senate seats this cycle will make it very difficult for Democrats to win the Senate in 2020, when two vulnerable Democratic Senate seats are up — Alabama and New Hampshire — along with four vulnerable GOP seats — Colorado, Iowa, Maine and North Carolina.

While the Senate outlook is increasingly bright for Republicans, the House looks almost guaranteed to flip to the Democrats next month. Republican strategists I talked with recently privately predicted Democratic House gains ranging from 25 to 50 seats.

The GOP’s problem in the House is the same as the Democrats’ problem in the Senate — the map.

Republicans sitting in upscale suburban districts — incumbents such as Virginia’s Barbara Comstock, California’s Mimi Walters and Colorado’s Mike Coffman — are counting down their final days in office, and “tribalism” is even endangering popular Republican incumbents in Democratic districts, like California’s David Valadao.

While some GOP strategists say they see suburban men who have been on the sidelines returning to the Republican column, others say there has been only a slight bump for the party in recent weeks.

One Republican observer said he thought as many as 20 or 21 of the 25 Clinton-supporting GOP districts could well flip, producing a large Democratic House wave.

Another Republican who believes the landscape is improving for his party agrees that the House will flip because there are simply too many strong, well-funded Democratic challengers in upscale districts.

For months, it has looked as if Democrats would capture the House and Republicans would retain the Senate. That remains the likely outcomes because there are essentially two different elections going on — one, in the Senate, in mostly pro-Trump, conservative, rural states; and one, in the House, in upscale, diverse, suburban congressional districts.

One of those groups of voters is electing the Senate, while the other group is electing the House. Given the deep division in the country and the very different outlooks of pro-Trump and anti-Trump voters, that should not come as a shock to anyone.

Both parties will try to improve their prospects in the final few weeks of the campaign. With Democratic voters and particularly better educated women engaged and energetic, it is up to GOP strategists to make sure their voters turn out.

Watch: As Midterms Enter Final Stretch, Senators Ready Their Rallying Cries