INDIANAPOLIS — Inside his campaign headquarters in Indianapolis, there’s a photo of U.S. Sen. Richard Lugar shaking hands with former U.S. Secretary Condoleeza Rice, one of the many Republican party heavyweights who’ve endorsed his return his office.

Pinned to the photo is a makeshift caption, intended to be humorous. “Thanks for the endorsement,” Lugar appears to be saying. “Can you make some phone calls now?”

It may not seem so funny anymore.

In the waning hours of a hard-fought campaign, Lugar volunteers and staff are calling Hoosiers across the state with an urgent plea to turn out for the primary election.

They’re working to turn what appears to be an ominous tide. Late last week, the independent Howey/DePauw Indiana Battleground Poll showed the longest serving Republican in the U.S. Senate was losing a lot of ground and may be headed toward defeat.

As of mid-afternoon Sunday, the Lugar campaign had made more than 1.4 million phone calls to voters who had been “micro-targeted” as likely Lugar supporters. More than 70,000 were made in the final weekend’s “get out the vote” push.

At the Lugar phone bank in Indianapolis, every time a campaign caller found a Lugar supporter on the other end, a bell would ring.

”It really helps morale,” said Wayne Stanley, a 25-year-old Kokomo native who’s running the Lugar phone banks. “You hear the bells ringing and you know this is working.”

The fear among Lugar backers -- and the hope of supporters of his intra-party rival Richard Mourdock -- is that won’t work enough to overcome what the Howey/DePauw poll found was a 10 point deficit in Mourdock’s favor.

After the news of the poll broke on Friday, the 80-year-old Lugar issued a kind of call to action to Democrats and independents by pointing out they could vote for him in the GOP open primary.

”I’m not asking anybody to cross over,” Lugar said. “I’m just saying positively to register your vote. Otherwise, if you do not, I may not be able to continue serving you.”

Ginni Schneider is a Mourdock volunteer working to put an end to Lugar’s service in the Senate. The Anderson retiree has been knocking on doors, making phone calls, and sending out e-mails to friends, family, and neighbors, urging them to get out to vote.

”He’s 80 years old, for God’s sake,” said Schneider. “It’s time for him to pass the baton.”

This is Schneider’s first real venture into a political campaign. She and her husband decided to become active after they met Mourdock in person. They found him to be a “true conservative” on fiscal and social issues that are important to them.

Schneider estimates that she’s handed out more 4,000 pro-Mourdock flyers and knocked on hundreds of doors.

”I’ve never been a person who wants fame,” she said. “But I’m a great cheerleader for other people. If I really love them, I’ll do anything to support them.”

The 60-year-old Mourdock, in his second term as state treasurer, has attracted enthusiastic support from Tea Party members like Schneider.

Garry Crone of Zionsville was among the Mourdock campaign volunteers who attended a “get out the vote” rally Saturday in Lugar’s home territory of Indianapolis. The Howey/DePauw poll showed Lugar was losing support in the city where he was once mayor.

Crone had met Mourdock at small gathering of supporters at a pizza parlor, Arni’s Restaurant in Lebanon.

”We connected right away,” he said. “I’ve never voted for anybody else but Richard Lugar. But not this time.”

Craig Kline of Linton brought his young son, Asa, to the rally. He said he’s been campaigning for Mourdock in his mostly pro-Democratic neighborhood and finding some support.

”Mourdock is clearly the anti-establishment guy,” said Kline, who sported a hat emblazoned with the unofficial Tea Party logo of a coiled snake and the words Don’t Tread on Me.

Kline is convinced Mourdock’s strength was sealed when Tea Party members across the state coalesced behind a single candidate, rather than fielding several candidates as they did in the 2010 primary, which was won by the GOP establishment’s candidate, now U.S. Sen. Dan Coats.

”We’ve been told we’re dying out,” Kline said of the Tea Party movement. “But it’s just that we don’t do as many rallies anymore. Now we’ve got boots on the ground.”