Twice under President Barack Obama, Republican lawmakers precipitated acute crises of governance. Now, as Donald Trump's Washington nears a government shutdown, Republicans accuse Democrats of doing the same thing.

The 2011 debt crisis and 2013 government shutdown bear a surface similarity to the current impasse. In the first two, a Republican-controlled House demanded policy concessions in return for raising the federal debt limit and keeping the government open; now the Democratic minority wants concessions.

But the differences in circumstances outweigh the similarities — and not just because Republican now hold undivided control of the government. In reality, Democrats are not doing the same thing.

In 2011, having won control of the House the previous November, Republicans demanded massive spending cuts as a condition of preventing a government default. By the time Senate Republican leader Mitch McConnell engineered an escape strategy, the U.S. suffered the first-ever downgrade of its credit rating.

Republicans eventually forced Obama and his party to accept massive spending cuts — but those cuts proved so much deeper than American voters would support that they've been rolled back. Republican leaders themselves no longer support them.

In 2013, Republicans forced a shutdown as part of their quest to wipe out Obamacare. Since Obama remained president and Democrats still controlled the Senate, they had no prospect of success.

Nor was public consensus behind them, though overall public opinion on Obamacare was marginally negative. As the shutdown dragged on, Americans blamed Republicans more than Democrats, and Republicans eventually surrendered.

Thus Republicans had twice halted government over objectives they lacked the political support and institutional power to sustain.

The current standoff is far different.