Bob Vander Plaats, president of The Family Leader, greets Iowa Senate candidate Joni Ernst (R) following her speech at the Family Leadership Summit in Ames, Iowa, Aug 9, 2014. The pro-family Iowa organization is hosting the event in conjunction with national partners Family Research Council Action and Citizens United. [Photo/Agencies]

DES MOINES, Iowa - On a night when Republicans got a dose of very good news in the election battle that could decide who controls the US Senate, three potential Republican presidential candidates flocked here to speak to more than 1,000 conservative Christians at an annual dinner.

Iowa state Sen. Joni Ernst, the GOP candidate for US Senate in what has been one of the tightest contests in the country, made a surprise appearance at the Faith and Freedom Coalition dinner, just minutes after the Des Moines Register released its first poll on the race, showing Ernst ahead of Democratic Rep. Bruce Braley, 44 percent to 38 percent.

"I'll tell you what. We are going to win this seat back this November!" Ernst said to the cheering crowd of Christian conservative voters.

Ernst and Braley are locked in a battle to replace retiring Democratic Sen. Tom Harkin, who is coming to the end of his fifth term in office. Republicans may gain control of the Senate if they can take the Iowa seat as part of their effort to pick up six seats. Ernst's campaign had seen positive polling numbers for its candidate in the past week, and the Register poll validated its sense that she has gained an edge over Braley, even after withstanding a barrage of negative TV ads for several weeks.

Ernst and Braley will debate for the first time Sunday night, and the Register poll only increased the stakes for the already crucial face-off.

Looking on from the audience as Ernst spoke inside a building at the state fairgrounds were Republicans US Sen. Ted Cruz of Texas, Louisiana Gov. Bobby Jindal and US Rep. Paul Ryan of Wisconsin. Cruz and Jindal had been scheduled to speak at the dinner, but Ryan came from a fundraiser he was headlining across town with Ernst.

Ryan had planned on flying in and out of the state without a public appearance. It would have fit a pattern: The 2012 vice-presidential nominee has talked about a potential 2016 run, and was making his third trip to Iowa since 2012. But he has done less to build an organization than have others, and has shown genuine reservations about undergoing the brutal primary process. Cruz and Jindal, meanwhile, show all the signs of plowing full speed ahead toward launching presidential candidacies at some point after the November midterm elections.

Ryan's decision to come to the dinner, however, did a little bit to keep him in the 2016 conversation. In addition, it allowed Jindal and Cruz to appear alongside Ernst, instead of just appearing in the state for political events only tangentially related to the midterm elections. Many Iowans in both parties resent when national politicians and the press focus on the presidential election during the heat of the local contests in the midterms.

The audience response to Ryan was tepid. Veteran conservative organizer Ralph Reed gave a friendly but not overly enthusiastic introduction to Ryan, and the biggest cheer for the Wisconsinite came when he announced the results of the Register poll. Ryan spoke for just a few moments about his philosophical differences with the Obama administration, denouncing the president for growing government to the point where it is "off the rails."

It was Jindal's fourth trip to Iowa since 2012. The Rhodes scholar son of immigrants from India is overlooked in the 2016 conversation much of the time, and many Republican insiders feel he lacks the stature and presence they think is required of a presidential candidate. But Jindal's advisers believe he can gain ground with activists and grass-roots voters through retail politicking, and that he can surprise those who now underestimate him.

Jindal gave a lengthy, 38-minute speech, wearing a lapel microphone and walking around the stage in the same way that Cruz has made a habit of doing. He mixed personal stories with criticisms of the Obama administration, and reserved some of his sharpest remarks for outgoing Attorney General Eric Holder, whom he clashed with over Louisiana's school voucher program.

"How sweet it is to hear that Eric Holder is about to be out of a job," Jindal said. "I would just ask that our next attorney general actually read the Constitution of the United States before he becomes the attorney general."

Cruz, the conservative firebrand, was making his seventh trip to the Hawkeye State since 2012. He has demonstrated over and over again in the past year that he has captured the imagination of the Christian conservative grass roots, and on Saturday night he received the loudest, most enthusiastic ovation, even though the audience had been listening to speeches for two and a half hours by that point.

Cruz, like Jindal, gave a nearly identical speech to the one he delivered Friday at a similar gathering in Washington. He talked at length about the plight of Christians imprisoned or killed for their faith around the world, and criticized US President Obama for not pressing foreign governments about the issue of religious liberty.

"We need a president who stands up and says, let them free," Cruz said. He also dinged the administration for conducting talks with the government in Tehran, charging that at the United Nations meetings in New York they were "swilling chardonnay with the Iranian government."

And Cruz drew laughter when he joked that Hillary Clinton had been arrested trying to jump the fence outside the White House.