Editor's note: Tom Mann is a senior in governance studies at the Brookings Institution and the W. Averell Harriman Chair. His most recent book, co-authored with Norman Ornstein and now out in paperback, is "It's Even Worse Than It Looks: How the American Constitutional System Collided With the New Politics of Extremism."
(CNN) -- One talking point frequently used by Republicans to justify shutting down the government while trying to overturn the Affordable Care Act is that the House and its Republican majority are more representative of Americans' views than President Barack Obama and the Democratic Senate.
That is preposterous and beside the point.
The ACA is law. End of story. The House Republicans' attempt to nullify a duly-enacted law violates the norms of our constitutional system. It is reckless economically and an egregious affront to our democratic form of government.
House Republicans have every right to press their views in Congress but not to threaten to blow up the U.S. and global economy by shutting down the government and threatening public default
We have elections for all three key players -- the president, the House and the Senate. If Republicans want to change the law, they must do it the old-fashioned way: Persuade the others to accept their position or win control of the White House and Senate.
House Republicans lost ground in the 2012 elections, lost the national vote for the House by over a million votes and retained a majority only because of favorable districting.
Obama won re-election by 3.9 percentage points and got an overwhelming victory in the Electoral College. Senate Democrats retained their majority despite having to defend more than twice as many seats as the Republicans.
House Republicans represent a distinct minority of public sentiment. They carelessly generalize from the echo chambers of their safe districts to the national electorate.
Polls show a majority of the public opposed to shutting down the government to kill or amend Obamacare. A majority of Americans also oppose its repeal or defunding.
Moreover, a significant portion of those who don't like the law say it doesn't go far enough.
But public opinion doesn't matter at this point. The Constitution provides for an orderly process of making laws and building agreement between chambers of Congress and branches of government.
Blackmail, extortion, hostage-taking and brinksmanship are the tools of terrorists, not legislators.
The opinions expressed in this commentary are solely those of Thomas Mann.