Republican Bill Cassidy’s victory over incumbent Sen. Mary Landrieu (D-LA) in the Louisiana general runoff election on December 6 gave the incoming Republican majority 54 seats in the Senate, three seats more than the party needs to control the chamber.

In a runoff for Louisiana’s 5th congressional district, Republican physician Ralph Abraham defeated Monroe, La., Mayor Jamie Mayo, a Democrat. Abraham will succeed Rep. Vance McAllister (R-LA). In addition, Republican Garret Graves defeated former Louisiana Gov. Edwin Edwards in the 6th District.

One race is outstanding in Arizona’s 2nd congressional district between Rep. Ron Barber (D-AZ) and Republican Martha McSally. The Washington Post reports that if McSally wins—she is currently in the lead—it will be the single biggest GOP majority since the beginning of the Depression.

In January, Republicans will hold at least 246 of 435 seats, which matches the number they held during President Truman’s administration, according to the Associated Press. Combined with the Republican takeover of the Senate, Congress will be all-GOP for the final two years of President Obama’s second term.

For more information on recent elections, read NACDS’ Summary of 2014 State Elections