Republicans and Democrats are still locked in a tight battle to create new congressional districts that they can win. But Republicans have used their control over the once-a-decade redistricting process in most key states to shore up many vulnerable incumbents.

The Post’s freshly updated Redistricting Scorecard shows that we now have a good idea about the amount of seats that could change hands in 27 of the 43 states that have to draw new maps (seven other states have just one congressional district and thus don’t have to draw new lines).

With the process now more than half over, we can project that Republicans would gain one congressional seat from the process, while Democrats wouldn’t lose or gain any seats.

More and more, the two sides look like they will fight to a draw in the battle to create new districts, leading some to suggest that the process will be a wash.

But that misses a key point: namely, the GOP’s work to shore up its already-huge majority.

According to a Fix review of the scorecard, Republicans have created nearly a dozen districts they have a good shot at winning in the 18 states where they control all levers of the redistricting process – both re-jiggering districts that are currently held by Democrats and in states that are getting new congressional seats due to population gains. They are also likely to lose a seat in both Louisiana and Ohio, where population losses meant a GOP seat had to be eliminated. So in those 18 states, Republicans are on pace to gain upwards of 10 seats.

Perhaps more helpful, Republicans have also shored up more than a dozen of their freshmen and more vulnerable members, including Reps. Austin Scott (Ga.), Todd Young (Ind.), Thaddeus McCotter (Mich.), Dan Benishek (Mich.), Tim Walberg (Mich.), Renee Ellmers (N.C.), Steve Stivers (Ohio), Pat Tiberi (Ohio), Steve Chabot (Ohio), Bill Johnson (Ohio), Mick Mulvaney (S.C.), Joe Wilson (S.C.), Blake Farenthold (Texas), Quico Canseco (Texas) and Sean Duffy (Wis.).

Democrats, by contrast, control the process in just seven states, in which they don’t have many vulnerable districts to bolster, but they have been able to create at least four districts where they now have a good chance to win. They are set to lose one seat in Massachusetts. So in the seven states where they control redistricting, the Democrats’ current net gain is projected at three seats.

Where Democrats have evened the score is in the six states where an appointed commission has drawn new lines. Despite most of these commissions’ nonpartisan goals, they have drawn maps in Arizona and California that are likely to net Democrats about four seats and cost Republicans about three seats.

And in the remaining 12 states, where control over the process is split between both parties, Republicans and Democrats are currently fighting to a tie.

With still more than one-third of the states yet to draw maps, though — and lots of legal action left to occur — things will continue to evolve. And possibly in a pretty major fashion.

Here are some of the key questions that will be answered in the months ahead that could tip the balance to either party:

* What happens in Florida? This is the biggest mystery of all. Republicans control the process, but the party also holds more than three-fourths of House seats in a swing state.

The GOP is optimistic that it can protect its 19 incumbents and secure the state’s two new Republican-leaning districts, but it won’t be easy. Democrats, meanwhile, hold out hope that a pair of constitutional amendments passed by voters last year will limit the GOP’s ability to draw a partisan map. If the new laws have teeth, Democrats think they could actually gain a handful of seats.

* How aggressive will Pennsylvania Republicans get? The Pennsylvania GOP was burned 10 years ago when it spread itself too thin, didn’t do enough to shore up many of its most vulnerable members, and those members went on to lose mid-decade.

Republicans eventually won back almost all of those seats, but they are again faced with a map on which many of their incumbents are vulnerable, and they may be wary of trying to target Democratic seats again. With the state losing one of its 19 seats, Republicans appear most likely to draw together Democratic Reps. Jason Altmire and Mark Critz. But do they also target Democratic Rep. Tim Holden’s Republican-leaning district?

* How do impending lawsuits pan out? Republicans are set to gain lots of seats in Texas, while Democrats are set to do the same in Illinois, but the other side is suing in both states to have the map struck down. This is an issue in Texas, in particular, where the Justice Department is fighting the Republican map and could spoil the GOP’s plan to gain three seats.

Other states where legal action could affect things in a significant way include Arizona, Maryland and Ohio. In Ohio, Democrats are threatening to put the Republican map to a referendum. The legal process is always important in redistricting, largely because it’s so unpredictable.

* Does New York Gov. Andrew Cuomo (D) veto? The New York legislature hasn’t even proposed maps, but Cuomo is threatening to veto any partisan map.

The state legislature is split between Republicans and Democrats, so the map isn’t likely to overtly favor one party. The question is whether Cuomo would bristle at any kind of incumbent-protection map, which is what the legislature is most likely to produce. With 27 House seats at stake, Cuomo wields lots of power. And he hasn’t been afraid to wield it.