Senate Dems campaign group raised $5.8 million in December

The Democrats' Senate campaign arm raked in $5.8 million in December, outraising the Senate GOP campaign committee as both groups prepare for crucial elections in 2018. 

At the same time, the Democratic Senatorial Campaign Committee (DSCC) finished paying off the last of its election debt, and is entering the New Year with $19 million in its bank account. 

Politico first reported the DSCC's December fundraising haul. 

The committee's fundraising haul for the month and its cash on hand puts it ahead of the National Republican Senatorial Committee, which reported raising $3.4 million in December and ending the year with $15.3 million on hand.

Both groups are gearing up for a series of potentially pivotal campaign fights in 2018. While Democrats are hoping to make gains by capitalizing on President TrumpDonald John TrumpDems flip Wisconsin state Senate seat Sessions: 'We should be like Canada' in how we take in immigrants GOP rep: 'Sheet metal and garbage' everywhere in Haiti MORE's low approval ratings, the party is fending off Senate challenges in more states than Republicans are. 

Democrats are fending off challenges in 10 states that Trump won in the 2016 presidential election. 

Among the most vulnerable Democratic senators, according to the Cook Political Report, are Sens. Joe DonnellyJoseph (Joe) Simon DonnellyDems search for winning playbook GOP anxious with Trump on trade Blue wave of 2018 stops in Indiana and Missouri MORE (Ind.), Claire McCaskillClaire Conner McCaskillNSA spying program overcomes key Senate hurdle Senate campaign fundraising reports roll in Dems search for winning playbook MORE (Mo.), Joe ManchinJoseph (Joe) ManchinMcConnell to Dems: Don't hold government 'hostage' over DACA Lawmakers see shutdown’s odds rising Senate campaign fundraising reports roll in MORE (W.Va.) and Tina SmithTina Flint SmithPawlenty opts out of Senate run in Minnesota EMILY’s List president: Franken did 'right thing for Minnesota' Booker, Harris appointed to Senate Judiciary Committee MORE (Minn.), who took office last month after now-former Sen. Al FrankenAlan (Al) Stuart FrankenPawlenty opts out of Senate run in Minnesota EMILY’s List president: Franken did 'right thing for Minnesota' Dem pledges to ask all court nominees about sexual harassment history under oath MORE (D-Minn.) resigned amid sexual misconduct allegations.

But GOP-held seats in Tennessee, Nevada and Arizona are all considered vulnerable in 2018, according to Cook.