Liberals said Tuesday that there may be no other way out of a debt ceiling crisis than to invoke — or at least threaten to employ — the so-called nuclear option, an enormously contentious move that would allow the party to raise the national borrowing limit with 51 votes rather than 60. …

Liberal Democrats vow to ratchet up pressure on Senate Majority Leader Harry Reid (D-Nev.) to take the unprecedented step if Republicans refuse to give their party at least six votes to overcome a filibuster ahead of the first key debt ceiling vote, likely Saturday.

“The rules will have to change,” Iowa Sen. Tom Harkin said when asked how Democrats should respond if the GOP blocks the debt ceiling bill. “If we don’t [have the votes to break a filibuster], then I think it’s time to recognize the new realities that I have been talking about for a number of years. And the reality is that this ain’t your grandma’s Senate.”