U.S. Rep. Jerry Moran, of Hays, stands next to his wife, Robba, on Tuesday as she gives a thumbs up to his supporters after it was announced that he had won the Republican nomination for the U.S. Senate seat at a watch party organized by the Johnson County Republican Party at the Overland Park Marriott.

Overland Park ? Kansas Republicans on Tuesday chose U.S. Rep. Jerry Moran as their nominee for an open U.S. Senate seat in a primary race that saw both leading candidates fighting aggressively and sometimes bitterly for conservative GOP voters.

Kansas Rep. Todd Tiahrt checks the results on a laptop along with Doug Henkle, right, and Matthew Stroia, both volunteers for his campaign.

See a precinct-by-precinct breakdown of the results in the Republican and Democrat U.S. Senate races.

Moran overcame a strong challenge from fellow Rep. Todd Tiahrt and questions raised by Tiahrt supporters about Moran’s commitment to being conservative. With most of the vote counted, Moran had just shy of 50 percent to Tiahrt’s 45 percent, with two minor candidates splitting the rest.

For many GOP voters, a key issue was which longtime congressman would be more aggressive in fighting President Barack Obama and his fellow Democrats. Many Republicans saw either as an acceptable nominee, and both enjoyed strong ratings from groups such as the National Rifle Association, the American Conservative Union and the National Right to Life Committee.

Moran will face Lisa Johnston, a Baker University administrator from Overland Park who emerged from a five-person Democratic race that also included state Sen. David Haley, of Kansas City, and Charles Schollenberger, a former newspaper reporter and editor from Prairie Village.

The Moran-Tiahrt race was the hottest of the year in Kansas — and among the nastiest in the last generation, as the two candidates hashed over small differences in their records. Moran painted Tiahrt as a Washington insider, while Tiahrt suggested Moran was hiding a moderate streak from voters.

Some voters saw Moran’s campaign as the less negative.

“I think Tiahrt got a little bit too nasty for me at the end,” said Pat Drummond, a 54-year-old self-employed house cleaner from the Kansas City-area suburb of Overland Park who voted for Moran.

But Tiahrt supporters blamed the negative tone on Moran, pointing to mailers from his campaign.

Tiahrt promised to endorse Moran, and the new GOP nominee said he doubts he’ll have a difficult time attracting Tiahrt’s supporters. The two agree on some issues, such as eliminating federal income taxes in favor of a national sales tax and continuing the war in Afghanistan without setting a timetable for withdrawal.

Dozens of supporters chanted, “Jerry! Jerry! Jerry!” in the ballroom of the Marriott hotel in Overland Park, where Republicans planned to have a victory breakfast this morning.

“There are opportunities for us to try to make sure that there is no permanent division. Primaries within the family are a very difficult thing,” Moran said after his victory speech. “Our country is in desperate need of leadership. It’s way past time for Republicans to continue having bickering.”

At his own election-night party at the Wichita Airport Hilton, Tiahrt congratulated Moran as the state’s next senator and promised to work for GOP candidates.

“I do not want a Democrat senator from the state of Kansas,” he said.

Moran is expected to win the November election easily in GOP-leaning Kansas, which hasn’t elected a Democrat to the U.S. Senate since 1932. Johnston is making her first run for office.

The seat they’re seeking is held by Sam Brownback, a conservative Republican who is running for governor instead of seeking another term in the Senate. Brownback overwhelmingly won his GOP primary race against token opposition.

11:35 p.m. update

From the Associated Press:

Kansas Republicans have chosen Congressman Jerry Moran as their nominee for an open U.S. Senate seat in a bitter primary race where both candidates actively courted GOP conservatives.

Moran overcame a strong challenge from fellow Rep. Todd Tiahrt. The key issue for many voters was which longtime politician would be more aggressive in fighting President Barack Obama and his fellow Democrats.

Moran promoted endorsements from conservative senators such as tea party favorite Jim DeMint of South Carolina, while Tiahrt had the backing of former GOP vice presidential nominee Sarah Palin.

Baker University assistant dean Lisa Johnston won the Democratic nomination for the U.S. Senate.

Kansas hasn’t put a Democrat in the Senate since 1932.

11:29 p.m. update

Jerry Moran has won the Republican nomination for U.S. Senate, beating Todd Tiahrt in one of the closest primary races across the state.

He will face Lisa Johnston in the November general election.

Voters in Douglas County also elected Moran over Tiahrt. Moran received 54 percent of the county vote and 57.1 percent of the Lawrence vote.

View a precinct breakdown for this race.

10:43 p.m. update

Douglas County voters agreed with the rest of the state when it came to selecting Lisa Johnston for the Democratic U.S. Senate nomination.

Johnston received 31.3 percent of county votes and 32.4 percent of Lawrence votes. Her closest threat, Charles Schollenberger, received 18.2 percent of county votes and 18.3 percent of Lawrence votes.

View the precinct breakdown for this race.

10:30 p.m. update

Lisa Johnston has won the Democratic nomination for U.S. Senate. From the Associated Press:

A college administrator has won the Democratic nomination for the U.S. Senate.

Lisa Johnston, an assistant dean at Baker University in Baldwin City, overcame four others in Tuesday’s primary.

Johnston has worked 17 years in higher education and oversees support services for students at Baker. She lives in Overland Park.

She defeated state Sen. David Haley of Kansas City; Charles Schollenberger, a former newspaper reporter and editor from Prairie Village; Lawrence attorney and accountant Patrick Wiesner; and retired Shawnee railroad engineer Robert Conroy.

Kansas hasn’t elected a Democrat to the U.S. Senate since 1932.

9:53 p.m. update

From the Associated Press:

Kansas Congressman Jerry Moran held a narrow lead Tuesday night in a contentious battle for the Republican nomination for a U.S. Senate seat.

Moran had a tough challenge from fellow Congressman Todd Tiahrt. With more than half of the precincts reporting, Moran had 48 percent of the vote to Tiahrt’s 46 percent, with two minor candidates splitting the rest.

Five Democrats were vying for their party’s nomination, but none was expected to beat either Moran or Tiahrt in the November general election.

Both Moran and Tiahrt courted GOP conservatives and tea party participants.

9:48 p.m. update

All Douglas County precincts are now reporting, and have voted in favor of Jerry Moran for the GOP U.S. Senate nomination. Moran received 54 percent of the county vote and 57.1 percent of the Lawrence vote.

Todd Tiahrt received 38.6 percent of the county vote and 35.7 percent of the Lawrence vote. Tom Little received 3.9 percent in Douglas County and 3.6 percent in Lawrence. Robert Londerholm received 3.4 percent of the county vote and 3.6 percent of the Lawrence vote.

See the precinct breakdown for this race.

9:27 p.m. update

With 867 of 3,316 precincts reporting, Moran and Tiahart are separated by less than 600 votes. Moran has a slight lead with 64,604 to Tiahrt’s 64,018.

It’s still Johnston over Schollenberger with 873 precincts reporting. Johnston has 12,028 votes followed by Schollenberger with 8,657, Haley with 8,319, Wiesner with 6,217 and Conroy with 3,664.

8:52 p.m. update

The race between Tiahrt and Moran is getting close, folks. With 414 of 3,316 precincts reporting, Moran only leads Tiahrt by four percent.

Lisa Johnston still has 10 percent on Schollenberger with 419 precincts reporting. After Jonston and Schollenberger, that race looks like this:

• Haley, 19 percent
• Wiesner, 16 percent
• Conroy, 10 percent

8:19 p.m. update

Johnston and Moran continue to lead the races for U.S. Senate. Johnston’s lead is a close one. With 126 of 3,316 precincts reporting, she’s up on Schollenberger by 12 percent.

Moran still has 55 percent of the vote to Tiahrt’s 38 percent, but now 120 of 3,316 precincts are reporting.

7:57 p.m. update

Early results show Jerry Moran has the lead on opponent Todd Tiahrt in the GOP race for U.S. Senate. With 18 of 3,316 precincts reporting, Moran has 55 percent of the vote to Tiahrt’s 38 percent.

Lisa Johnston is leading the Democrat’s race for U.S. Senate with 36 percent of the vote and 21 of 3,316 precincts reporting. Schollnberger is her closest threat with 24 percent of the vote.

7:43 p.m. update

Lisa Johnston is taking an early lead over Charles Schollenberger, Patrick Wiesner, Robert Conroy and David Haley in the Democratic race for the U.S. Senate nomination. Johnston has 38.8 percent of the vote. Her closest threat is Schollenberger with 23.5 percent.

Jerry Moran is building an early lead on Todd Tiahrt, Tom Little and Robert Londerholm. Moran currently has 68.9 percent of the Republican vote.

— Online editor Whitney Mathews contributed to this story.