Almost every Iowa poll for months has shown the U.S. Senate race as a dead heat, and that razor's edge environment was evident in the urgency of the messages from Hillary Clinton and Democrat Bruce Braley in their first joint campaign appearance. 

"If you want a senator who doesn't believe Iowa is for sale to the highest bidder, please do everything you can for the next six days," the former secretary of state told about 400 people who gathered on Wednesday in a union hall in Cedar Rapids. "You don't want to wake up the day after the election and wish you had done more."

It was just Clinton's second visit to Iowa since her third-place finish in the state's 2008 caucuses, something she referenced in her remarks.  "I have concluded that Iowans take politics really serious," Clinton said. "You test your candidates. You actually force them to be the best they can be." Then, she paused for a moment and chuckled. "I understand that," she said. "They have to be willing to answer the tough questions, which Bruce has been willing to do and his opponent has not," Clinton said. "It truly seems like it should be disqualifying in Iowa of all states to avoid answering questions."

Clinton was referencing Republican candidate Joni Ernst's decision to skip editorial board meetings with some of the state's largest newspapers, including the Des Moines Register. "With Bruce Braley, you have somebody who has not only answered questions, endlessly, from one end of the state to the other, but has withstood a withering barrage of negative ads and innuendo and is still standing strong on your behalf," Clinton said.

The Clinton appearance, which will be followed on Saturday with one by her husband, former President Bill Clinton, illustrates the determination of both parties to use every weapon, every surrogate, every dollar they can spare to drag their candidate over the finish line in a race that could determine control of the Senate.

The former first lady criticized the "flood of unaccountable, outside money trying to muddy the waters here in Iowa to drown out your voices," and she tailored her remarks to appeal to women voters who are seen as being critical to Braley's political prospects. 

"This race comes down to one question above all others: Who's on your side?" Clinton said, echoing a talking-point of the Braley campaign.  There are "big differences" between Braley and Ernst when it comes to reproductive rights for women, support for minimum wage and many other issues. "You never worried where Tom Harkin stood," she said in a nod to the Democrat retiring from the seat. "You will never worry where Bruce Braley stands. He's a fighter for Iowa."

Lisa Peloquin, a real estate referral agent from Cedar Rapids, was one of those who attended the Clinton-Braley event. She said she thinks of herself as an independent voter, but is a volunteer for Braley. "I would normally support a woman, finally, to represent the state of Iowa for national office," said Peloquin, noting how the state has never elected a woman to Congress. "But I cannot support this woman for office. I don't support her views. They are too extreme for me."

For Peloquin, Clinton is another story. After backing President Barack Obama in the 2008 and 2012 Iowa caucuses, she said she is open to Clinton. "In 2008, I thought her opponents would drag all of Bill Clinton's ghosts into the race," she said. "Now, Hillary has established herself as a former secretary of state and she stands on her own feet."

 Braley told those gathered that he needed them to throw themselves into get-out-the-vote efforts over the next few days. "What you do when you walk out of this union hall is going to determine the future of Iowa," he said.

Ernst and Braley are competing in one of the most closely watched Senate races this year. A Quinnipiac University poll released Wednesday shows Ernst at 49 percent and Braley at 45 percent, with just 5 percent of likely voters still undecided. The survey showed independent voters, the state's largest voting bloc, backing Ernst over Braley, 50 percent to 41 percent.

The Clintons and Braley have a bit of a checkered past. Back in 2007, when Hillary Clinton was running for president, Braley was a U.S. House member being courted by all camps for his endorsement ahead of the Iowa caucuses. After Clinton worked hard for it, he endorsed John Edwards. And, after the North Carolina senator's campaign imploded amid a sex scandal, Braley embraced the junior senator from Illinois, Barack Obama. She and her husband are renowned for being both fiercely loyal and for holding political grudges, but if there was any awkwardness in Wednesday's appearance with Braley it wasn't obvious. Braley referenced a fundraiser Clinton headlined for him in 2006 and also presented her with a University of Iowa outfit for her new granddaughter, Charlotte.