With just under 100 days until the 2018 midterm elections, the Senate map continues to contain plenty of uncertainty. But Democrats’ optimism (and GOP panic) about the House doesn’t stretch to the other side of Congress.

Democrats are facing a historically bad Senate map, playing defense in deep red territory with far fewer options for pickup opportunities than most years. That means in many of the country’s key Senate races, President Trump remains an ace in the hole rather than an albatross for Republicans — and Democrats face a much tougher task at netting the two seats needed for a 51-49 Senate majority than would be expected given the president’s unpopularity nationally.

Democrats began the election cycle expecting to lose some Senate seats and holding zero hope for winning back Senate control. But Sen. Doug Jones’ (D-AL) shocking upset victory over the fatally flawed Roy Moore last winter and Trump’s continued struggles with voters have given them hope of minimizing losses — and an outside shot at winning Senate control if everything breaks their way.

There are at least a dozen Senate seats that could be competitive, and seven races that strategists in both parties view as the toughest fights. Democrats see solid opportunities to pick up seats in a trio of Senate races, and Republicans are bullish about knocking off four Senate Democratic incumbents. The general consensus among numerous Senate campaign strategists TPM talked to in recent days is the most likely outcome is a wash, with net gains of a seat or two for Republicans more likely than Democrats’ hopes of gaining seats — but small changes in the national environment, like a marginal improvement for Trump nationally or his trade war damaging him with GOP-leaning rural voters, could tip all the races one way or the other. And there’s always the chance that a candidate implodes.

“If the election were held today I think we’d win two Democratic seats and they’d win two Republican seats. But I fear things could get worse. You’ve still got to give the edge to Republicans on holding the Senate, but if everything breaks against Republicans together, we could find ourselves in the minority,” one GOP campaign strategist told TPM.

In true wave elections, the party with the advantage tends to win most or all of the close Senate races unless candidates self-immolate a la Moore or Todd Akin — that was true for the GOP in 2014, and for Democrats in 2008 and 2006.

“If there are seven tossup Senate races at the end, someone’s going to win five,” said one senior Democrat.

That could catapult Democrats to an improbable majority in the Senate — or lead to losses of two or more seats for them if things break the other way.

But the usual dynamic may not be quite as true this year. Trump’s numbers are weak enough, and Democrats are fired up enough even in red states, to suggest a wave, but the GOP base remains intensely loyal to the president and fairly excited to vote. That matters, especially since Democrats are defending five states where he won by at least a 20-point margin. Most true wave elections have one side much more enthusiastic to vote than the other, and while Democrats have a clear enthusiasm gap polls suggest the GOP base isn’t as depressed in rural areas as it was the last time Democrats swept to congressional control more than a decade ago.

That means that Democrats are feeling better about their chances in the Senate than they did early last year — but they could very well win the House and still lose seats in the upper chamber.

“I think we’ll see Republicans emerge with a number that is sustainable to hold the [Senate] majority in 2020 and Democrats with a majority in the House that’s big enough to govern but doesn’t put it out of reach for 2020,” said one top GOP strategist. “Every time I look at the Senate I want to expand the map [with resources], and every time I look at the House I want to build the walls higher.”

Party loyalists are unsurprisingly more bullish about their own party’s chances for gains than the other side. But there’s a fair amount of agreement over which states are going to be the closest — and where each party is in the most trouble. Here’s what they have to say.

Democratic pickup opportunities: Nevada, Arizona, Tennessee

Democrats have a strong chance of flipping three Senate seats their way, with a two others that are interesting enough to keep tabs on but are unlikely to flip.

In Nevada, strategists in both parties say Rep. Jacky Rosen (D-NV) has a better than even chance at knocking off Sen. Dean Heller (R-NV). The fast-diversifying state has trended blue, and while Heller got lucky when Danny Tarkanian dropped his primary challenge early this year, the senator’s votes to repeal Obamacare and moves to embrace Trump in a state the president lost in 2016 were already on the record by then.

Some Democrats are even more bullish about the race to replace retiring Sen. Jeff Flake (R-AZ) — one strategist called it a “chip shot” for his party.

Democrats have coalesced behind Rep. Kyrsten Sinema (D-AZ), a bulldog of a candidate who’s posted huge fundraising figures and has carefully burnished her profile as a moderate since winning her seat in Congress after earning a much more liberal reputation in the statehouse.

On the other hand, Republicans are staring down a major primary headache. While they believe Rep. Martha McSally (R-AZ), the establishment favorite, will prevail for the nomination over former state Sen. Kelli Ward (R) and former Maricopa County Sheriff Joe Arpaio (R), a pair of hardline conservatives, she’s had to work hard to woo immigration hardliners in the deeply polarized state in order to be able to stave them off. That makes it much harder for her to swing back to the center should she win her August 28 primary, and has given Sinema a massive fundraising start.

Public and private polls in both states have found Democrats ahead, though Republicans say Heller and McSally have looked better in recent numbers.

Democrats are also bullish about former Tennessee Gov. Phil Bredesen’s (D) chances against Rep. Marsha Blackburn (R-TN). Bredesen remains popular in the red state from his time in office last decade and has been using his vast personal wealth to self-fund his race, giving him an early advantage on the air.

Bredesen has held a narrow lead in most early public and private polls, though that may not hold up given the state’s strongly conservative tilt and is partly because of his higher name identification.

Republicans scoff at the idea that they’ll blow an open race in a state this red — “We’re going to hang onto Tennessee unless she botches things royally,” one Republican who knows the state well told TPM.

But Democrats think that Blackburn’s bill that critics charge made the opiate problem significantly harder to combat could damage her badly with GOP-leaning voters, and could give Bredesen just enough space to eke out a victory.

Democrats hope they get lucky and can win in ruby-red Mississippi if Republicans nominate hardliner Chris McDaniel over appointed Sen. Cindy Hyde-Smith (R-MS) in the all-party November election. But even if that happens, the runoff election will occur after the rest of the Senate. If that seat will determine Senate control, it will make it much harder for former U.S. Agriculture Secretary Mike Espy (D) to make the race about McDaniel and much easier for Republicans to nationalize the race, so it’s unlikely that this seat can get Democrats to victory.

Rep. Beto O’Rourke (D-TX) has also been printing money against Sen. Ted Cruz (R-TX), but few strategists in either party think there’s a real chance he can pull off a win in the Lone Star state.

That’s the good news for Democrats. But they’re on defense in more places than they’re playing offense.

Democrats on defense: North Dakota, Missouri, Indiana, Florida

Democrats believe they’ve been able to shrink the map since early last year. Ten incumbents sit in states Trump won, including five in states Trump won handily, but most strategists think just four are in real trouble: Sens. Heidi Heitkamp (D-ND), Claire McCaskill (D-MO), Joe Donnelly (D-IN) and Bill Nelson (D-FL).

Republicans believe they’re almost certain to beat Heitkamp after seeing months of polling showing her trailing Rep. Kevin Cramer (R-ND). Democrats believe the race is tied and she could grind out a win driven by her strong personal brand and missteps from loose cannon Cramer, but admit she’s their most vulnerable incumbent given the state’s deep red hue. She won her last race by less than 2,000 votes, and that might be the best-case scenario for her this time around.

Two other red-state Democrats are in for bloody battles, though strategists believe they’re in better shape. There’s some debate about whether McCaskill or Donnelly is in more trouble, but most Democrats believe both are in coin-flip races at best, while many Republicans think they’ll beat one or both of them.

“There’s significant differences between North Dakota and the next-toughest states,” one top Senate Democratic strategist told TPM.

McCaskill is a dogged campaigner and has a major cash advantage over her opponent, Missouri Attorney General Josh Hawley (R). But after a rough spring, Republicans believe he’s turned the corner — and she’s faced a spate of tough headlines in recent weeks. On top of that, McCaskill has done little to break with her party compared to the other red-state Democrats, making it harder for her to win cross-party support.

Many Republicans admit that Hawley is a lackluster, stiff campaigner, and worry he will get outworked in the race’s closing months and could still fall short in a year where the Democratic base is more ginned up to vote in spite of Trump’s strong numbers in the state. The race is tied right now, with Republicans more confident than Democrats that they’ll pull this seat out.

Donnelly has done more to woo independents and Republicans than McCaskill, but he’s not in as good financial shape (it’s a lot harder to woo Democratic donors when you’re splitting with them on key issues like backing Supreme Court Justice Neil Gorsuch).

Democrats are hopeful that they can sufficiently tar businessman Mike Braun (R) as a fat cat out for himself, and have leaned heavily into attacks on his record of selling imported goods and accusations that he mistreated his workers. Republicans think they can neutralize or win this fight by slamming “Mexico Joe” for his stake in a family company that outsourced jobs.

Strategists in both parties think their guy can win this seat, but most expect it’ll be a tight race through the finish.

Republicans are also bullish about Florida. Wealthy Gov. Rick Scott (R) is pouring in huge sums and will vastly outspend Sen. Bill Nelson (D-FL). Democrats worry the longtime senator hasn’t shaken off the rust fast enough and is facing a much more aggressive candidate.

Scott’s approval ratings are near the highest in his eight years as governor and has led in some recent public polling, though pollsters in both parties think the race is unlikely to be won on either side by more than a point or two (it is Florida, after all). The diverse swing state is a lot easier than a lot of Democrats’ other defensive terrain, and Trump’s weak standing could hurt Scott, who has tied himself to the president, more than other GOP candidates. But strategists in both parties think the race could go either way.

“I’m worried about Florida,” said one Senate Democratic strategist. “It’d be terrible if we hold onto these really tough seats but lose Florida.”

Republicans are also hopeful they might be able to put another seat seriously into play, most likely against red-state Sens. Jon Tester (D-MT) or Joe Manchin (D-WV). Both have posted strong polling numbers and face flawed opponents, but are running on very tough terrain. Some Republicans still hope they could force a tough race against Sen. Tammy Baldwin (D-WI) or potentially even Debbie Stabenow (D-MI) or appointed Sen. Tina Smith (D-MN), but none of those races appear particularly close right now.