ABC News’ Teddy Davis reports: A rift is beginning to open in the Democratic Party on the question of how aggressive President Obama should be in pushing his agenda through Congress. The moderates – led by Indiana Sen. Evan Bayh (D), the head of a new centrist group in the Senate – are urging the president to consider the economy-wide implications of imposing carbon caps. The centrists are also urging Obama to craft his health-care plan in a way that is capable of winning some Republican support. The liberals – led by the progressive Campaign for America’s Future – are painting Bayh’s group as obstructionists. Robert Borosage, the co-director of the Campaign for America’s Future, sent an email to supporters on Thursday blasting Bayh and his moderate allies for wanting to "force" President Obama "to get a super-majority of 60 votes" in the Senate. "They don’t want the President to use Senate budget rules that only require a simple majority of 51, which would smooth passage of the changes voters demand on health care and clean energy," writes Borosage. Picking up on the "Blue Dog" nickname that moderate-to-conservative Democrats have adopted in the House, Borosage urges his supporters to take on Bayh’s group and "train these disobedient Blue Dogs to listen to the people. And the people stand with the President on his budget and his priorities." For now, the Obama administration is leaving its options open on the budget reconciliation question. Speaking at a Tuesday lunch with reporters sponsored by the Christian Science Monitor, Obama budget director Peter Orszag said that it is not the president’s preference to pass his agenda with a process which would only requre a simple majority vote in the Senate. He was quick to add, however, that it is "premature" to take any option off the table and argued that the budget reconciliation process has been used more often than its detractors like to acknowledge.