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CNN  — 

Democrats know that if former Vice President Joe Biden wins the presidency, he’ll need a Democratic-controlled Senate to accomplish a good part of his agenda. An examination of the Senate landscape reveals good news for them.

The Democrats’ chance of wresting control away from Republicans has increased over the last few months. They are clearer favorites to take back Congress’ upper chamber, though the race for Senate control is still well within the margin of error.

To gain a majority of seats, Democrats need a net pickup of between three seats (if Biden holds onto his lead over President Donald Trump, as his vice president would become the tie-breaking vote) or four seats (if Trump wins).

Democrats now have a little more than a 7-in-10 (70%) shot to win at least 3 seats and a little more than a 6-in-10 (60%) chance of winning at least 4 seats. In early May, it was 3-in-5 (60%) for at least a 3 seat gain and 1-in-2 (50%) for a 4 seat shift.

But then as now, there’s a lot of uncertainty. We still have three months to go before the election. Applying a margin of error (based on past performance), it’s possible Republicans could retain control and potentially even gain a seat or two. Democrats, meanwhile, could run the table and have a double-digit gain.

The reasons Democrats are likely to do well remain the same as it was in May. They have a lead north of 8 points on the generic congressional ballot. Additionally, Democrats only need to defend 12 of the 35 seats up for election this year, so they continue to have a wide array of choices. They have at least a 1-in-10 (10%) chance in two dozen (24) seats. They likely won’t win all of these seats, but even if they lose a bunch of them, they still have a real shot at a majority.

Democratic chances to win in a number of these races have gone up since May.

Specifically, Democrats are doing considerably better in a number of races that were either tossups or previously leaning toward the Republicans:

  • North Carolina was best described as a tossup in early May. The polling, however, has moved in Democrat Cal Cunningham’s direction. Although Republican Sen. Thom Tillis is still very much in the hunt, Cunningham now has about a 2-in-3 (67%) chance of defeating the incumbent.
  • Iowa was a race that was leaning in Republican Sen. Joni Ernst’s direction. The recent polling, however, has actually given Democrat Theresa Greenfield the smallest of edges. Given the Republican tilt of Iowa, Ernst could close. For now, the race is a tossup (1-in-2 shot for both candidates), as opposed to May, when Ernst was a 3:1 favorite.
  • Republicans now only have small advantages in both Georgia Senate races. Republican Sen. David Perdue has about a 3-in-5 shot (60%) of beating Democrat Jon Ossoff in the regularly scheduled election. That’s up considerably from May thanks to Ossoff holding close to Perdue in the polls. In the special election (with multiple candidates on both sides running in a jungle primary), the Republicans have closer to a 2-in-3 (66%) chance. The Republicans had just less than a 9-in-10 (90%) chance back in early May.

Beyond those four races, Democratic odds have not gone up greatly in any state.

Democrats, though, are now favorites to win four Republican-held seats: Arizona, Colorado, Maine and North Carolina. If they won all four, they’d be in a strong position to take control. In all of them, Democrats have at least a 2-in-3 (67%) chance. None of these are done deals by any stretch, though, and you could easily imagine Republicans winning a number of them.

Democratic chances have slightly improved in both Arizona and Colorado from about 3-in-4 (75%) in May to 4-in-5 (80%) now. In Arizona, Democrat Mark Kelly holds a 5 point or greater lead over Republican Sen. Martha McSally in most polls. There’s less high quality polling in Colorado, though Democrat John Hickenlooper holds similar advantages over Republican Sen. Cory Gardner.

Things are more dicey for Democrats in Maine. Democrat Sara Gideon remains the favorite over longtime Repubilcan Sen. Susan Collins, but Collins has generally kept the deficit at or under 5 points.

While Democrats are favored in four Republican-held seats, Republicans are favored to pick up just one Democratic held seat. Republican Tommy Tuberville leads in the polls and has a little less than a 9-in-10 (90%) chance of defeating Democratic Sen. Doug Jones in the deep red state of Alabama.

Indeed, Republicans have worse than a 1-in-10 chance (10%) in every other Democratic held seat.

Democrats, on the other hand, have multiple, even beyond the ones we’ve already listed.

The top of that list includes Montana, where Democrat Steve Bullock, the state’s governor, actually has the tiniest of edges over Republican Sen. Steve Daines in the polls. Bullock is a slight underdog at a 2-in-5 chance (40%) because Montana leans Republican on the presidential level, which is up from a little more than a 3-in-10 shot (30%) in May.

Next up is Kansas, where Democrat Barbara Bollier has about a 1-in-4 (25%) chance in a state that hasn’t elected a Democratic senator in nearly 90 years. The big question mark in this historically red state remains who her fall opponent is. If it’s arch-conservative Kris Kobach, Kansas’ former secretary of state, Bollier’s chances rise. If it’s someone else (probably Roger Marshall), they go down.

Three other traditionally states on the outer radar for Democrats are Alaska, South Carolina and Texas. Republican incumbents are favorites in all three, though Democrats have roughly between a 1-in-10 (10%) and 1-in-7 (about 15%) in all of them.

Kentucky is the only race that was above this 1-in-10 threshold for the Democrats in May that no longer is. Thanks to stronger polling, Senate Majority Leader Mitch McConnell now has a 19-in-20 (95%) chance of retaining his seat, as compared to roughly 6-in-7 (85%) in May.

Overall, though, the picture is rosier for the Democrats than it was a few months ago. The fight for the Senate leans in their direction. Republicans maintain a clear pathway to a Senate majority, but it’s narrower than it was in May.