WASHINGTON - After an 8-year-old in the D.C. area racked up a $1,400 bill on the iPhone game "Smurfs' Village," U.S. Sen. Amy Klobuchar fired off a letter to the Federal Trade Commission demanding better oversight of "in-app" sales.

"The most troubling aspect about this practice is the fact that these applications -- many of which are games -- are typically marketed toward children," the Minnesota Democrat wrote in her Feb. 8 complaint.

A month later, Apple announced it would tighten its billing practices for "smurfberries" and other purchases on newly downloaded applications.

Klobuchar pronounced herself satisfied, adding to a growing list of consumer victories on family issues that defy political definition, from swimming pool safety to a ban on lead toys.

At a time when Congress is more polarized than ever, Klobuchar is marching toward reelection next year as one of the most popular incumbents in the nation, having carved out a comfortable niche in the middle between the raucous extremes that dominate daily cable TV news.

A Republican challenger has yet to emerge, even as the Minnesota GOP hammers at what it calls the "myth" of her moderate image, connecting her to a voting record that largely aligns with more left-of-center Democrats like Sen. Al Franken.

But as Klobuchar pursues the pragmatic politics of constituent service and bipartisan dealmaking, she faces some frustration on the left, particularly among gay activists and environmentalists who see her playing it safe in the middle of the road.

"There are big, fundamental system change issues we have to address," said Steve Morse of the Minnesota Environmental Partnership, which has battled Klobuchar over climate change legislation and her support for a new Stillwater bridge over the St. Croix River. "Dealing with swimming pools is good and important to families, but it doesn't change the big drivers of our society."

Klobuchar, now in her fifth year in the Senate, recoils at the suggestion that she's playing small ball to get along in Washington. She points to her role as one of 14 senators who pushed the Obama administration for a bipartisan fiscal commission to tackle the nation's deficit woes.

Amid a budget stalemate that nearly shut down the government, Klobuchar calls the commission's recommendations as "the only grown-up thing we're looking at."

Those include proposals to deal with structural budget problems like Social Security, one of the most sacred cows of American politics. Klobuchar has signed on to the commission's plan to increase payroll taxes and trim benefits for high-end earners, as well as to slowly raise the retirement age by one year, which would keep the system solvent for another 75 years.

She also favors scaling back the mortgage interest deduction on homes over $500,000, an idea that has drawn heavy fire from the real estate industry.

"I've been willing to talk about these things in ways that some Democrats aren't," Klobuchar said.

'Need to be ready'

Despite approval ratings that hover around 59 percent, Klobuchar is taking no chances as she prepares for 2012, a presidential election year when Obama will be at the top of the ticket and Republicans can be expected to go for broke.

"We need to be ready for whatever the other side will throw at us in the coming months, and that means building a strong foundation -- early," Klobuchar wrote in a recent fundraising pitch to supporters.

What the other side has thrown at her so far is mostly a website with a graphic that depicts her morphing into Franken. Sponsored by the Minnesota GOP, it faults her for three key votes: Her support for Obama's health care overhaul, the $800 billion economic stimulus bill and a move to advance failed climate change legislation that Republicans dubbed "cap and tax."

"She has attempted to take a very low profile on some of the more polarizing votes in her record," said Michael Brodkorb, the state party's deputy chairman. While Klobuchar often touts her consumer and constituent victories, Brodkorb said, "what affects Minnesotans more are some of the key votes we have cited."

Klobuchar, like most Washington politicians, sides with her party in about nine votes out of 10. But she has carefully laid out a bipartisan track record on an array of popular proposals, such as simplifying international adoptions.

Since January she has introduced 12 bills, nine with Republican co-sponsors. Many of them focus on consumer protection and law enforcement, a hallmark of her past as Hennepin County attorney.

"She's pragmatic, smart and hard-working," said Sen. Jeff Sessions, the conservative Alabama Republican who worked with Klobuchar on the adoption bill. Politically, he added, "we don't always agree... but she's a delight to be with."

Klobuchar's personal popularity is key to the sorts of alliances needed to get anything done in the clubby atmosphere of the Senate. Privately, even some Minnesota Republicans say she's shrewd.

But as she fires up her campaign machine, Klobuchar still faces a balancing act. Her perceived centrism, real or not, could solidify her appeal with independents while alienating her base.

"Running in elections has a lot to do with motivating your supporters," Morse said. "A lot of Democrats saw that in this past cycle, when their base just didn't turn out."

While DFLers are unlikely to abandon the state's first elected female U.S. senator, Klobuchar has been willing to break with her base as needed. She supports removing gray wolves in Minnesota from the federal government's endangered list, introduced a bill mandating the sale of federal land to a northern Minnesota mining company, voted to exempt farmers from clean air legislation, and got behind the disputed Stillwater bridge, a position that put her crosswise with her political mentor, former Vice President Walter Mondale.

Gays also have been upset by her late decision to support the repeal of federal legislation restricting gay same-sex marriage.

"I don't get on every bill right away," Klobuchar said. Protecting her right flank at home, Klobuchar has supported the state's biofuels industry, worked to limit the tax on medical device companies under the health care law, and "stood up" for local auto dealers when federally supported carmakers sought to close them down.

But she makes no bones about the little things that endear her to regular people, like the adoption bill.

"If anybody thinks bringing back tens of thousands of kids who would be orphans ... is small, it's not small," Klobuchar said. "It's a big thing to a lot of families."

Kevin Diaz is a correspondent in the Star Tribune Washington Bureau.