The Republican base seems to be happy about the narrowing of their party, Sen. Ben Nelson (D-Neb.) suggested in a video interview posted Friday.

"I think the problem is their base seems to be narrowing for them, and that base is happy about narrowing, saying, 'If you don't like us, leave.'" Nelson, a centrist Democrat who opposed President Obama's budget, told CBS. "They are going to have to assess how they deal with their members, because there are fewer and fewer truly centrists on the Republican side."

Nelson predicted that centrists would retake the GOP in due time from more conservative members who've exerted strong influence over the party's direction in recent years.

"There are a lot of middle-of-the-road, centrist, moderate Republicans -- and they'll take charge of their party again; they'll come back," he said. "But at the present time, it seems to me that a group has almost taken charge of it and narrowed its base intentionally, and that doesn't really work that well in politics."

Nelson speculated that newly-minted Democratic Sen. Arlen Specter (Pa.) would also be spending time in the "penalty box" for breaking with the party in coming years.

Watch a video of the interview below:

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