United States President Barack Obama will stick to his policy agenda, including healthcare reforms, despite his Democratic Party's loss in a key Massachusetts election.
Scott Brown won the Senate seat to become Massachusetts' first Republican senator since 1972. The result means Republicans have enough Senate votes to impede the president's plans.
A senior presidential advisor says there will be a rethink on tactics but the substance of policy will not change.
Mr Obama has warned Democrats not to "jam" healthcare reforms through the Senate. He told ABC News that any vote should wait until the new senator had taken up his seat.
The election loss deprived Democrats a crucial 60th Senate vote they needed to pass the healthcare bill and push through other big measures on climate change and financial regulatory reform, Reuters reports.
The seat was left vacant by the death of Senator Edward Kennedy, and had been held by Democrats since it was won by John F. Kennedy in 1952.