Cowan sworn in as interim Massachusetts senator

Cowan, flanked by Sen. Elizabeth WarrenElizabeth WarrenWasserman Schultz: 'Sometimes you just have to take one for the team' Chelsea Clinton's big moment Kaine as Clinton's VP pick sells out progressive wing of party MORE (D-Mass.) Kerry, was sworn in by Vice President Biden. He is now the Senate's second black senator, and the only black Democratic senator.

He will serve until a special election to replace Kerry occurs in June. Democrats are likely to retain the seat, as Massachusetts Republicans have been unable to front a strong challenger since former Sen. Scott Brown (R-Mass.) decided against a run.

Reps. Edward MarkeyEd MarkeyTim Kaine backs call to boost funding for Israeli missile defense FCC chief pushes phone companies to offer free robocall blocking Markey floats bill bringing internet to developing world MORE and Stephen Lynch have both announced their intentions to pursue the Democratic nomination for the seat, and face a primary on April 30.

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