WASHINGTON - The political pendulum swung again for Pat Toomey last week.

Cheered by the left and chided by the right for his stance on gun laws in the spring, Pennsylvania's Republican senator saw those reactions reversed last week when he sided with GOP hard-liners at the end of the government shutdown.

On a high-profile vote to reopen the government and allow more borrowing to pay its bills, Toomey sided with Ted Cruz and the Senate's most conservative bloc to oppose the bipartisan deal.

"It was a very tough call," Toomey said in a telephone interview Tuesday as he discussed a vote fraught with political implications, especially as Republican poll numbers plunged amid the ugly showdown.

"I had no objection to reopening the government. . . . My main objection was combining that with several hundred billion dollars of additional debt that's piled onto our already excessive levels of debt with no reforms whatsoever," Toomey told The Inquirer. "Nothing that curbs the spending."

The topsy-turvy reactions on two of the year's biggest debates illustrate the fine line Toomey must walk: He won his seat in the 2010 tea party wave as a staunch fiscal conservative, but he represents a state that has trended Democratic in recent years.

"He's going to be walking this tightrope over the next three years of vacillating between his standing among the conservative base and making outreach to more moderate voters in the state," said Chris Borick, a political scientist at Muhlenberg College.

While conservatives were cheered, Democrats swiftly branded Toomey "Tea Party Pat." Marc Eisenstein, a spokesman for the Pennsylvania Democratic Party, said, "Toomey embarrassed his constituents and should be ashamed of himself."

Toomey had sought to distance himself from the GOP's most strident voices in the latest fight, saying he disagreed with threatening a shutdown to "defund" Obamacare. He called that "a bad idea" that could not succeed with President Obama still in the White House.

But when the deal to reopen the government after 16 days included plans to increase borrowing authority without finding savings elsewhere, he said it was more than he could stomach.

Democrats and numerous business groups had urged both parties to raise the debt ceiling to ensure that the country's bills get paid and head off a potentially disastrous default, and six House Republicans from the Philadelphia area supported that step.

Toomey was one of just 18 senators to vote against it. It was the second time in the shutdown drama that he sided with hard-liners such as Cruz (R., Texas), who led the fight to undercut Obama's signature health law.

After Toomey's April push for expanded background checks on gun buyers won plaudits from the likes of Mayor Nutter and former Gov. Ed Rendell, Democratic operatives saw the shutdown votes as a way to puncture some of Toomey's pragmatist credentials.

But it may have restored some of his backing from the conservatives who helped him into office and had chafed at his role in the gun debate.

"People were watching him and not sure how conservative he was," said Anastasia Przybylski, the Bucks County-based Pennsylvania director for the tea party-affiliated Freedomworks.

Does she now feel reassured?

"I do," Przybylski said. "That's what I thought we were getting out of Toomey: one that was going to stand up to business as usual."

A delicate balance

Much of Toomey's challenge comes from facing two distinctly different electorates.

In 2010, amid a national tea party wave, Toomey ran as the true Pennsylvania conservative, pushing longtime Sen. Arlen Specter out of the GOP and winning with a message focused on fiscal responsibility.

But last November he saw Obama and fellow Democrats dominate statewide voting, the latest example of Pennsylvania going blue in presidential years. One of those years is 2016, when Toomey faces reelection, and Democrats are eager to take him on.

Once the head of the Club for Growth, the fierce small-government group that helped lead the charge against Obamacare, and a champion of punishing "Republicans in Name Only" - he wrote a Wall Street Journal op-ed headlined "In Defense of RINO Hunting" - Toomey has had to strike a more delicate balance in recent months.

For example, he dined with Obama earlier this year before speaking at the Heritage Foundation the next day.

His gun bill brought grumbles from a conservative conference in his home state and a rebuke from the Heritage Foundation, led by Toomey ally Jim DeMint, a former senator. The think tank's political arm said conservatives "expect more from Pat Toomey."

After the gun bill, another high-profile break with the right could have been damaging.

"He doesn't want to necessarily push that relationship, especially when his 'no' vote on this might be forgotten come 2016," said Borick, who noted that Toomey's votes on the shutdown did not affect the final outcome since the Senate vote was lopsided, 81-18, in favor of the deal.

A key factor: Toomey's vote on the shutdown and debt ceiling were on fiscal issues, the core of his political work.

"When presented with a vote to raise that debt by another several hundred billion dollars without a shred of reform, I just felt on balance it was better to oppose that and to make the point that we need to find a solution to this disastrous fiscal situation," Toomey said Tuesday.

He pointed to $6 trillion in deficit spending projected over the next decade by the nonpartisan Congressional Budget Office.

As for Democratic attacks, he said, "One thing I'm quite certain of, they will make those accusations no matter what I do. . . . how I vote doesn't matter."

His standing in his own party is still strong enough that his name as been floated in news reports (always anonymously) as a potential GOP gubernatorial candidate if Gov. Corbett continues to struggle.

"I am very much focused on my work as a senator," he said Tuesday. "This is an extraordinary responsibility that I have and I take it very, very seriously, and it has been consuming all of my energy."

(An aide later e-mailed to add: Toomey has endorsed Corbett, and the endorsement stands.)

Some Pennsylvania conservatives said Toomey's standing was never really in doubt.

Fred Anton, president of the Pennsylvania Manufacturers Association and organizer of the conservative Pennsylvania Leadership Conference, recalled how the audience was restive when Toomey arrived there this year, but gave him a standing ovation when he promised to continue battling Obama on fiscal issues.

"The profile of any legislator or any senator is a complicated one," Anton said. "There are a lot of nuances."

Don Adams, president of the Independence Hall Tea Party political action committee said: "Most reasonable conservatives understood that the senator represents multiple constituencies . . . not just those that voted for him."

Toomey will have a hand again in the next big fiscal deadline. He is one of the negotiators set to take part in bipartisan talks to try to reach a long-term budget deal by mid-December.

"I hope that we'll take an approach where we're sensible and realistic about our expectations on both sides," Toomey said.

One thing he said should not happen is any further attempt to tie defunding Obamacare into budget talks.

"That was not a good idea last time," he said. "It wouldn't be a good idea this time."