U.S. Reps. Gabrielle Giffords' and Raúl Grijalva's re-election races were too close to call early today as the vote count continued overnight.

Both Democrats held leads of a few thousand over Republican challengers Jesse Kelly and Ruth McClung, respectively, with at least 35,000 Pima County votes still to count.

Shortly before 11 p.m. Grijalva gave a victory speech to supporters at his campaign headquarters, but with many uncounted ballots also remaining in the outlying counties that make up parts of both districts, the races remained close even early this morning.

"I will not let you down, I will not sell you out, and I will not misrepresent you," he told his supporters. "We're not going back with a renewed sense of caution, we're going back with a new sense of purpose."

He acknowledged Republicans had taken over the majority of the House of Representatives.

His message to the new majority: "We're going to hold you accountable for the things you can't do," Grijalva said.

Grijalva's strong grass-roots campaign style saved him on Election Day, despite anger over his call for a boycott of the state in response to SB 1070, he said.

"They had the bludgeon of the boycott and they had John McCain and really we were running against John McCain's organization and their pros," Grijalva said, in a nod to McCain's advertising for McClung. The two Republicans also shared an office space late in the campaign.

Early into the evening vote counting, McClung said she knew she'd have to be patient.

"I understand statistics well enough to know anything could happen," she said.

But the fact that the race appeared so close was an accomplishment, she said.

"I believe we've shown America there is no safe district."

The race in the southwestern part of the state was ignored by pundits and analysts for months, and even McCain and Gov. Jan Brewer said they thought McClung was a long shot when they first met her.

Then, in the final month of the campaign, the numbers tightened and several national political analysts said the race was neck-and- neck or too close to call.

Neither Kelly nor Giffords claimed victory Tuesday in the tight race in District 8.

"It looks like it's gonna be tight like we thought it was, but I think we're gonna do it," Kelly told a Republican crowd in Tucson.

While waiting for more decisive results, he celebrated other Republican House victories nationwide.

"So the American people already chose liberty," Kelly said of those clear victories.

The two were separated by a couple thousand votes, and Kelly told supporters, "I'm not going anywhere."

Giffords' campaign pointed out she was winning among early voters.

"This election will go down as one of the angriest, most difficult, challenging and painful" in recent memory, Giffords told a Democratic crowd Tuesday night, but she said she was proud of the race she ran.

Like Grijalva, she noted the Democrats have lost the House majority.

"We've lost a lot of good friends who fought against eight years of bad economic policies," she said..

Grijalva was winning among Pima, Pinal and Santa Cruz county voters. That put McClung's strength in Yuma, Pinal and La Paz counties.

Giffords was winning in Pima and Santa Cruz counties, plus in early voting districtwide. Kelly was carrying the Election Day voters and Pinal and Cochise counties.

The race is tighter than Giffords' previous two congressional elections, which she won by more than 10 percentage points over her Republican opponents.

If Giffords wins, her momentum can be attributed to her campaign strategy to frame Kelly as too extreme for the district, and using TV and Web ads to show she has broad support, said Barbara Norrander, a professor in the School of Government at the University of Arizona.

"She did a good job at having different constituencies featured in her ads. The idea is that everyone would see a commercial that would look something like their concerns," Norrander said.

Giffords also focused on her support from Republicans, veterans, teachers, seniors and others in the swing district, while Kelly's endorsements were mostly from conservative groups.

Kelly said Saturday he was effective because people are fed up with the Democrats' decisions and the direction of the country.

"This year, if you're running on a message of limiting government, cutting taxes and giving people health-care freedom, then the people will carry you to victory," Kelly said.

Kelly's momentum can be at least partly attributed to the national anti-Democrat or anti-incumbent sentiment in this midterm election, Norrander said.

"You just have people concerned about the way the country is going, and they want to just vote the incumbents out," she said.

At every turn during the campaign, Kelly highlighted Giffords' votes for controversial legislation such as the health-care overhaul and the bank bailouts.

Libertarian Steve Stoltz' campaign focused on the Constitution, and he was receiving a sliver of the votes in the race in District 8.

Libertarian George Keane and independent Harley Meyer were on track to receive a similarly small portion of the votes in District 7.

Sometimes tight races can cost votes for third-party candidates, Norrander said.

"If it's a tight race, people think it might be wasting their vote to vote for the third-party candidate and that they might have more of a voice if they vote for one of the major parties," she said.

The race in District 7 followed some of the same narrative as in District 8: Grijalva highlighted some of McClung's positions that he said didn't fit the district, but her message was built around his call for a boycott against the state earlier this year in response to the SB 1070 immigration law.

Grijalva won his four previous House elections with more than 60 percent of the total votes..

Contact reporter Andrea Kelly at akelly@azstarnet.com or 807-7790. Reporters Alex Dalenberg, Clayton R. Norman and Becky Pallack contributed to this report.