Senator Arlen Specter, who has served as a Republican in Congress for nearly 30 years, announced Tuesday that he has switched parties and will now join the majority Democrats, according to dpa. The Pennsylvania senator's defection bolsters Democratic control of the Senate and enhances President Barack Obama's ability to push through his ambitious legislative agenda in Congress. "Last year, more than 200,000 Republicans in Pennsylvania changed their registration to become Democrats," Specter said. "I now find my political philosophy more in line with Democrats than Republicans." Specter, 79, was likely to face a strong challenge within the Republican party for the nomination for the 2010 election. Conservative Republicans were angry Specter voted in favour of Obama's 787-billion-dollar stimulus package in February.