UPDATE 2-Big bank "break-up" idea gains ground in Congress

* Independent Senator Sanders introduces break-up bill

* Legislation also under consideration in House

* Sanders would give Treasury 90 days to identify firms (Adds Kanjorski, Frank, Miller comments, background, byline)

By Kevin Drawbaugh

WASHINGTON, Nov 6 (Reuters) - An independent U.S. senator on Friday introduced a bill that would give the government the power to identify and break up financial firms that are "too big to fail," an idea that is catching on.

"If an institution is too big to fail, it is too big to exist," said Senator Bernie Sanders in a statement.

"We should break them up so they are no longer in a position to bring down the entire economy," he said.

Sanders is an independent outside the U.S. political mainstream. But he is not the only one looking at break-ups.

Representative Paul Kanjorski, the Democratic chairman of the capital markets subcommittee in the U.S. House of Representatives, is working on a break-up power amendment.