Senate trench warfare reached new heights this week as Republicans blocked votes on two bills that have broad bipartisan support.

The filibusters of the Shaheen-Portman energy efficiency bill on Monday and a business-backed tax cut bill on Thursday had little to do with the content of the bills. Republicans attributed their blockade to the fact that they weren’t able to offer the amendments they wanted to offer.

“This is what parliamentary warfare looks like,” said Sarah Binder, a leading Senate expert and a professor at George Washington University. “I think the filibuster of the tax extender and energy bills — both carefully negotiated by committee leaders in a bipartisan fashion — suggests yet another deterioration of the Senate’s legislative capacity. The combination of Senate rules and competitive, polarized parties makes the Senate near ungovernable.”

On Thursday a measure to revive expired tax breaks for companies on research and development, among other incentives, failed 53-40. The only GOP senator to join Democrats was Mark Kirk (IL). Republican leaders wanted to offer amendments, including one to repeal Obamacare’s medical device tax, but Democrats blocked it. So they filibustered the legislation.

“It had nothing to do with policy,” said Senate Finance Ranking Member Orrin Hatch (R-UT), who filibustered the bill even though he supported it. “It had to do with how we proceed. And frankly I think a message was sent today.”

On Monday the energy efficiency bill fell to a 55-36 vote, winning no Republicans other than Sens. Rob Portman (OH), Kelly Ayotte (NH) and Susan Collins (ME). Republicans wanted to tack on an amendment requiring approval of the Keystone pipeline and another to unwind the wind energy tax credit. Reid offered to vote on Keystone as a standalone bill, which could be vetoed by the president, and Republicans refused.

“This useless, mind-boggling obstruction is what continually grinds the wheels of the Senate to a halt,” Senate Majority Leader Harry Reid (D-NV) said. “So to my friends who want to know how we can make things better here in the Senate, I say: put an end to obstruction for obstruction’s sake.”

Senate Minority Leader Mitch McConnell (R-KY), in a floor speech Thursday, lamented that Democrats have “turned the Senate into a graveyard of good ideas and open democratic debate.”

There is merit to the Republican complaints. Reid has prevented the minority from offering amendments by using a tactic known as filling the tree more often than his predecessors, according to Congressional Research Service data. He seeks to tightly control amendments by cutting deals ahead of time, partly in an attempt to protect his vulnerable Democratic members from taking tough votes, and partly because he says Republicans are abusing the process with bad-faith show votes. But Reid is correct that this GOP minority’s obstruction has escalated to unprecedented heights.

“In all my years in the Senate I’ve never seen anything like this. All but the most routine bills are subject to filibusters,” said Jim Manley, a former top spokesman for Reid who left in 2010 to become a lobbyist. Manley said the majority leader opposes an open-amendment process because he has been blindsided in the past by “completely off-the-wall” Republican amendments relating to personhood or gun legislation, which aren’t always relevant to the underlying bill.

The partisan rancor has escalated since Democrats triggered the “nuclear option” in November to eliminate the 60-vote threshold for most presidential nominees. Republicans responded by forcing delays on all judicial nominees — even the ones with broad bipartisan support.

“The American people need to know what’s happening to their Senate. This body exists to ensure that the citizens of this country have a say in what their government does,” McConnell said. “It’s the citadel of our democracy — the place where we guarantee that no one in this country is cut out of the legislative process. … Yet today, we have a Democratic majority that’s turned this body right on its head.”

The laments from Reidland are also biting.

“It’s gotten so bad,” Manley said, “that Senator Reid is probably going to have to ask permission to go to the men’s room sometime and it’s going to be denied.”