When U.S. Sen. Pat Toomey took office just under two years ago, movement conservatives were elated.

In Toomey, they had a true believer; a rigid fiscal conservative who was articulating tea-party positions a full decade before the tea party even came along.

But a funny thing happened once Toomey arrived in Washington. He became a Republican that Democrats could work with. Toomey supported the repeal of "Don't Ask, Don't Tell." He co-wrote three job-creating bills with Democrats, and got them enacted. He even - as part of a failed budget deal - proposed $300 billion in new revenue.

None of this went unnoticed by Pennsylvania Democrats. They already knew Toomey to be an unusually capable politician, with a quick mind and a mastery of fiscal detail. With these nods at moderation, Toomey, they figured, might end up playing a central role in hammering out a long-term tax and spending compromise.

"Even if they won't admit it on cable television, I think most people recognize there's going to have to be some bending by both sides, and Pat Toomey is going to be an important voice in helping construct that path," David L. Cohen, the Comcast vice president and former chief of staff to Mayor Ed Rendell, told me earlier this year. It's a sentiment that other prominent - and moderate - Pennsylvania Democrats share.

Which is why it is so disappointing that Toomey is staking out an extreme position on the looming vote over the debt ceiling.

This isn't the fiscal cliff. Rather, it's the next round in the seemingly endless series of fiscal chicken Democrats and Republicans play in Washington.

At issue is whether to raise the national debt limit. This used to be a routine process, typically accompanied by a number of symbolic "no" votes from the party not in power. But in 2011, Republicans used the debt ceiling to extract a deficit-reduction package from President Obama and Congressional Democrats.

Toomey was a debt-ceiling hard-liner last year. And it looks like he plans to be one again, running the risk of shaking worldwide confidence in the ability of the United States to honor its debts in order to force more budget cuts.

This isn't just a bad idea, it's a reckless one. And it's not just Democrats who think so. Big-time GOP fund-raisers and supporters on Wall Street have no interest in repeating the debt ceiling drama of 2011, which led Standard & Poor's to its first-ever downgrade of the U.S. credit rating.

Toomey's office did not respond to an interview request, but Roll Call quoted him as downplaying the consequences of a debt-ceiling collision on Dec. 13: "Is a temporary disruption worse than a full-blown debt crisis?"

Also, like last year, Toomey is saying the Obama administration can avoid defaulting on loans by paying those debts first, and by shorting other obligations (Senate salaries might be a good place to start). This may or may not be workable.

But even if that gambit could be pulled off, the government would have to slash spending by about $100 billion a month. Cutting spending that dramatically, and that quickly, would surely slow the economy and may tip it back into recession.

This is the choice Toomey and his allies are setting up. Do what we ask, or the economy and the U.S. credit rating get clobbered.

Toomey does earnestly believe that the deficit is one of the nation's biggest problems. So we should expect him to vigorously seek to reduce spending. But Obama was just reelected, and Republicans lost seats in both chambers this fall. Democrats are not inclined to blink during another debt-ceiling showdown.

Granted, you can't look at the long-term spending forecasts without realizing that retrenchment is not just necessary, but inevitable. Still, there's a not very fine line between looking for legitimate leverage to advance your policies and manufacturing a crisis. Toomey is doing the latter.

The economy isn't the only potential casualty here. There is also Toomey's career to consider. If he is on the wrong side of this issue, and the United States does default, expect Toomey's political prospects to be snuffed out overnight. All the goodwill Toomey has carefully built up among moderates will vanish.

That would be a shame. To date, Toomey has shown himself to be one of Pennsylvania's most capable and intelligent lawmakers. It will be hard to see him in the same light if he insists on smacking into the debt ceiling, concussing both the economy and U.S. standing in the world.