Tea Partiers are the most enthusiastic advocates of America's system of government, with its divided powers, checks and balances and representative government. So it's ironic that their innovative organizing techniques have revealed a major weakness in America's system of government.

Republican members of Congress feel intense pressure from tea party activists to stick to a principled conservative agenda. Any deviation from the conservative line is met with a flood of phone calls and a credible threat of a primary challenge.

But Democrats control the Senate and the White House. They're not interested in signing onto the  tea party's conservative agenda. And traditionally, this kind of standoff has been resolved by compromise. Leaders from both sides would negotiate a compromise and then sell it to their members.

But largely thanks to the  tea party, House Speaker John Boehner doesn't have much leverage over his members. He can't credibly offer to compromise with President Obama. As Obama has realized that, he has become less and less willing to compromise himself, leading to the current standoff.

No compromise

Our system of divided powers often requires negotiation. And negotiation works best when all parties don't just think about the present, but also the future. Good negotiators want to get the best deal they can today, but they also try to build a relationship that will make it easier to reach the next deal. That means being willing to meet the other party halfway and looking for deals that are good for both sides.

But what do you do when you offer concessions and the other party doesn't reciprocate? For the past two and a half years, Barack Obama has faced this dilemma. He has offered concessions to help reach agreement with Republican leaders, but they haven't reciprocated. To the contrary, each time Democrats have agreed to cut spending, House Republicans have used the new figure as a new baseline for the next round of negotiation.

In 2011, Democrats agreed to $39 billion in cuts (in one fiscal year)  to avert a government shutdown. A few months later, they agreed to an additional $2.1 trillion in cuts (over 10 years) as part of a deal to raise the debt ceiling.

The majority of those cuts took the form of across-the-board "sequestration"— indiscriminate cuts to virtually all discretionary programs. A "supercommittee" was supposed to come up with a more sensible package of cuts. But negotiations failed, so spending cuts were due to kick in at the start of 2013. A last-minute deal in January  delayed those cuts until March, but the parties couldn't agree on a plan to replace them.

The result of all this cutting is that, adjusted for inflation, discretionary spending levels have fallen dramatically in the past three years:

(Center for American Progress)
(Center for American Progress)

The new, lower level of spending then became the Democratic position in the latest round of negotiations. House Republicans wanted spending to stay at the lower post-sequester levels and they wanted to delay Obamacare by a year.

Meanwhile, Republicans have not given an inch on Democrats' desires for higher tax revenue. Taxes did go up for high earners at the start of 2013, but that increase was scheduled by Congress more than a decade ago. Republicans have steadfastly opposed any other proposals to increase tax revenue.

And despite Democrats' flexibility, there seems to be no end in sight for the Republicans' strategy of perpetual brinksmanship. So far, the GOP has tried to use the threat of shutdown or default to extract policy concessions in March 2011, August 2011, February 2013, March 2013 and now October 2013. There's every reason to think that if Obama had made more concessions last month to avert a shutdown, Republicans would have come back for even more in 2014.

In short, Obama is negotiating with a party that always demands further concessions and is never willing to reciprocate. After a certain number of rounds of this, any rational negotiator is going to dig in his heels and refuse to give more ground.

Short-term thinking

In a narrow sense, the Republican strategy has been a success, cutting hundreds of billions of dollars from the discretionary budget. But it has two big flaws. The obvious one is that Obama finally called Republicans' bluff and allowed the government to shut down, and the public has overwhelmingly blamed the GOP, which could damage the party's prospects in future elections.

But the more subtle problem with the strategy is that brinksmanship over the discretionary budget is unlikely to fix America's long-term fiscal problems. Those problems are largely caused by the growing cost of entitlement programs such as Medicare and Social Security. These "mandatory" programs aren't subject to annual appropriations, so brinksmanship over appropriations bills isn't likely to change them.

In past negotiations, Obama has signaled a willingness to accept some cuts to entitlement programs, but only as part of a "balanced" package that includes some tax increases.

A rational Republican leader would have recognized some time ago that it's in the long-term interest of the Republican Party and the conservative movement (not to mention the country) to cut a deal with the president in which conservatives get some of their long-term policy priorities in exchange for giving Democrats some of theirs. Such a deal would help to burnish the party's image while making possible long-term fiscal reforms that they can't get by manufacturing a new crisis every few months.

The tea party problem

So why hasn't John Boehner done that? Because the tea party has emasculated the nominal leaders of the House Republican caucus. Boehner has so little control over his members that he can't credibly offer Democrats significant policy concessions.

Boehner's impotence was vividly illustrated last December, when Congress was debating how to deal with the automatic tax hikes that were scheduled to take effect at the start of 2013. Boehner tried to pass a bill, known as "Plan B," to cancel scheduled tax hikes for everyone making less than a million dollars. He believed that the move would strengthen his hand in negotiations with the White House, which only wanted to cancel the tax hike for families making less than $250,000.

But  tea party activists portrayed Boehner's legislation as a tax hike, and helped defeat it. That left him with little leverage in subsequent negotiations, since Democrats could get the upper-bracket tax hikes they wanted without lifting a finger. So a few days later, Republicans were forced to accept a deal that canceled the tax increase only for families making $450,000 — a worse outcome from the  tea party's perspective.

So why does the  tea party have so much power? A big reason is the threat of primary challenges. As The Post reported at the time, "several senior GOP aides said that many of the Republicans were wary of voting for Plan B" because it would draw a primary challenger who would portray it as a vote to raise taxes.

Another factor has been the abolition of earmarks, a reform pushed by  tea party activists. In the past, leadership could withhold earmarks from members of their caucus who refused to vote the party line. Now that source of leverage is gone.

As a result, Boehner can't credibly offer significant concessions in negotiations with Democrats. He can't credibly offer higher taxes in exchange for spending cuts because grass-roots  tea party activists will be able to intimidate many of his caucus members into voting against them. He can't even promise an end to brinksmanship, because the same grass-roots outrage that has forced him into a confrontational posture in the past will probably do so again in the future.

In a sense, the  tea party has made the Republican party the most democratic political party American politics has ever seen. Grass-roots activists exercise more power over the decisions of congressional Republicans than ever before.

Unfortunately, this is proving self-destructive. A party that's effectively leaderless can't formulate a coherent plan and execute it. That leads to a confused political strategy and, even worse, an incoherent policy agenda.

And in our system of government, a dysfunctional Republican Party can easily produce a dysfunctional government. Divided government requires compromise to function. And compromise can only happen if congressional leaders can credibly negotiate on behalf of their caucuses.

Tea party activists like to emphasize that we're a constitutional republic, not a direct democracy. Some have even called for the repeal of the 17th Amendment that established the direct election of senators. Returning to a Senate elected by state legislatures would probably be overkill, but the  tea party is right that our system of government depends on elected representatives being somewhat insulated from the day-to-day passions of the people who elected them.

The  tea party's rapid-response activism and the constant threat of primary challenges has made it difficult for Republican members of Congress to exercise the kind of independent judgement the Founders envisioned. That is producing a kind of slow-motion constitutional crisis, as our elected leaders find it harder and harder to reach the compromises necessary to keep the system functioning.