Democrats on Tuesday won a key state Senate race that will give them the majority in their chamber — but they still won’t actually control the state Senate.

​With nearly 80 percent of precincts reporting, Democrat ​Shelley Mayer topped her GOP rival, Julie Killian, 58-percent to 42-percent, forcing, forcing Killian to concede the race around 10:15 p.m.

Meanwhile, Luis Sepulveda ​trounced​​ Patrick Delices and Pamela Stewart-Martinez ​with nearly 90 percent of the votes ​in the heavily Democratic Bronx.

The seats were vacated last fall when George Latimer became Westchester County Executive and Sen. Ruben Diaz, Sr. took a city council seat.

Though the wins by Mayer and Sepulveda give Democrats 32 of the 63 seats in the Senate, their elections are not expected to change the balance of power in the Senate, as they​ could have.

That’s because one Democrat, Brooklyn Sen. Simcha Felder, said Tuesday afternoon that he would continue to vote with Republicans until the end of session in June — regardless of the outcome of the special election.

Gov. Cuomo, however, vowed to immediately increase pressure on the stray Dem to return to the fold.

“The Governor’s position is clear,” said Press Secretary Dani Lever. “The Democrats must unify to take back the majority. This conversation will continue in the morning.”

Cuomo recently persuaded a rogue group of Democrats to dissolve the Independent Democratic Conference after the group helped the GOP retain its power in the Senate for several years.

Felder is now the lone Democrat voting with Republicans and keeping them in charge of the chamber.