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Yard signs supporting U.S. Senate candidate Richard Mourdock in Columbus, Ind., on April 23. Mourdock went on to beat incumbent Sen. Dick Lugar in a primary race that received national attention, and a flood of money from outside Indiana.

It's happening in several congressional races, in states like Nebraska, Montana and Ohio — millions of dollars from out-of-state donors and outside groups are fueling candidates' war chests.

Last week in Indiana, outside money helped Richard Mourdock beat out six-term incumbent Sen. Dick Lugar in the GOP primary.

On Wednesday, WCPN's David C. Barnett reports for NPR's Morning Edition about the congressional race in Ohio's 9th District. The Republican challenger there is Joe Wurzelbacher, aka "Joe the Plumber," the guy who rose to fame in 2008 by tangling with then-candidate Barack Obama. The incumbent Democrat is Marcy Kaptur, and $3 out of every $4 in the race has come from donors who don't live in Ohio's 9th.

When did so many Americans decide races outside their backyards were important enough to back financially?

NPR's science correspondent, Shankar Vedantam stopped by Morning Edition with recent social science research that could provide some answers.

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President Obama in the Oval Office with Israel's Prime Minister Benjamin Netanyahu, May 2011.

Charles Dharapak/AP

President Obama in the Oval Office with Israel's Prime Minister Benjamin Netanyahu, May 2011.

President Obama tells both Israel and Iran through an interview with The Atlantic that "as president of the United States, I don't bluff," when he leaves open the possibility of a U.S. military strike against Iran's nuclear program. Obama made the comments shortly before a scheduled meeting with Israeli Prime Minister Benjamin Netanyahu at the White House, during which he will stress there's no need for an Israeli attack on Iran, and an appearance before AIPAC, the pro-Israel lobby. It also occurs during an election year when the votes of Jewish Americans could be crucial in Florida and elsewhere.

Maryland Gov. Mark O'Malley signed gay-marriage legislation into law Thursday evening, making his state the eighth to do so.

Virginia's legislature approved a controversial bill mandating ultrasounds for most women seeking abortions in the state. The anti-abortion bill, which was watered down to allow women to get external ultrasounds instead of a more invasive procedure, now goes to Gov. Rob McDonnell who has said he would sign it.

Washington State normally gets ignored by presidential candidates during the primary season. But as NPR's Martin Kaste reported on Morning Edition, the all-out delegate chase for the Republican presidential nomination has caused the candidates to visit Washington in hopes that winning the non-binding straw poll could help them eventually add to their delegate counts.

Enlarge Win McNamee/Getty Images

Sen. Jon Tester, D-Mont., faces a potentially tough re-election bid.

Win McNamee/Getty Images

Sen. Jon Tester, D-Mont., faces a potentially tough re-election bid.

On TV and radio in Big Sky Country, a battle is playing out that could help determine control of the U.S. Senate. It involves candidates and money, of course, but also the state's historic skepticism of outside interest groups.

As NPR's Martin Kaste reports for All Things Considered, third-party groups trying to sway control of the Senate see Montana as a relatively cheap date: In a state where a 10-day statewide media buy can be had for as little as $85,000, $2 million to $3 million can buy a lot.

That's about how much money Montana State University political science professor David Parker estimates that outside groups, like the U.S. Chamber of Commerce, have already spent on ads in the race for U.S. Senate.

In the Chamber's case, those are ads trying to oust Democratic Sen. Jon Tester.

Parker says those groups should keep in mind the state's longstanding suspicion of outsiders — whether it be big mining companies or the "coastal elites."

"Montana is a little different in this regard. We like to keep the outside at arm's length," Parker tells NPR's Kaste.

Enlarge Alex Brandon/AP

Lugar, in the Senate 34 years, faces a strong Tea Party challenge in next year's GOP primary.

Alex Brandon/AP

Lugar, in the Senate 34 years, faces a strong Tea Party challenge in next year's GOP primary.

Once, when you looked in the dictionary to find "most popular Republican in Indiana," a photo of Richard Lugar would invariably pop up.

And why not? He has won six Senate elections, more than any other Hoosier in history. In fact, in 2006, the last time he was on the ballot, Democrats didn't even put up a candidate against him. True, he has never been Mr. Warmth, and never wowed crowds with his speaking style. But he is hard working, bright, soft spoken, respectful and, though this is now in dispute, conservative.

It wasn't always in dispute.

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Sen. Jeff Bingaman (D-NM).

ASSOCIATED PRESS

Sen. Jeff Bingaman (D-NM).

Cue Another One Bites The Dust. Sen. Jeff Bingaman, a New Mexico Democrat has added his name to those senators, mostly Democrats, who are leaving the Senate.

Bingaman, in his fifth term, has been in the Senate since 1982. He's chair of the Senate Energy Committee.

As National Journal's Almanac of American Politics reports, Bingaman was a major proponent of the cap-and-trade proposal to rein in the greenhouse gases linked scientifically to global warming.

Bingaman is the fourth Democrat to announce his retirement. Two other senators, a Republican and independent, have also announced they won't seek re-election.

The announcement that Arizona Sen. Kyl won't seek re-election in 2012 ...

The decision by Sen. Jon Kyl (R-Ariz.) to opt out of a fourth-term bid was, to say the least, a surprise. At least to me. With the GOP having a good shot to regain the majority after next year's elections, Kyl, the number two Republican in the Senate, would have emerged with even more power and influence than he has today. Unlike the previous week's retirement announcement of Sen. Jim Webb (D-Va.), which was not unexpected, I thought Kyl, 68, was going to stick around for another six years.

... has led to speculation that Gabby Giffords might run. Um, a little premature?

More than a surprise however — more of disgust really — has been the growing number of pundits who say the impending opening is a great opportunity for Rep. Gabrielle Giffords (D) to run for the seat.

Excuse me? We're not talking about the same Gabby Giffords who is still recovering from last month's gunshot wound to the head, are we? The same person whose mental capacities are still uncertain, whose prognosis for a complete recovery is too soon to tell? That Gabby Giffords?