Since Pompeo bowed out of the race, the leading Democratic contender, state Sen. Barbara Bollier, has announced that she raised more than $1 million in her first quarter in the contest, unprecedented for a Democratic Senate hopeful in Kansas.
In the days following the Pompeo news, Bollier has received call-outs on Twitter from Democrats such as Sen. Chris Murphy of Connecticut and had record online fundraising, with more than $80,000 from 1,700 contributors, according to her campaign.
"It's very exciting," said Vicki Hiatt, chairman of the Kansas Democratic Party. "Several months ago, we didn't know which direction things were going. Now it looks like Democrats have a strong possibility of picking up a U.S. Senate seat."
Democrats in Kansas, a state that has been reliably red in national elections, have experienced a mini-surge over the past two years, with voters electing Laura Kelly governor and Sharice Davids, a lesbian Native American, to the U.S. House in 2018. Three Republican state legislators recently have changed their party affiliation from Republican to Democrat, including Bollier.
Pompeo was courted by Senate Majority Leader Mitch McConnell, R-Ky., for months and would have entered the race as a hands-down favorite for the seat. Now Republicans face a bruising primary battle between Kris Kobach, a former secretary of state and ally of President Donald Trump who lost the governor's race a year ago, and a host of ho-hum establishment candidates who have not inspired confidence in the Republican leadership.
When Kobach, 53, declared his bid for the seat vacated by retiring Republican Sen. Pat Roberts, the National Republican Senatorial Committee took the unusual step of denouncing his candidacy, saying it put both the Trump presidency and the Senate seat "at risk." An NRSC spokesman said this week that their position on Kobach has not changed.
Kobach - who built a national reputation as a campaigner against illegal immigration and as a proponent of Trump's border wall - beat then-Republican Gov. Jeff Colyer in the 2018 gubernatorial primary. But in the general election, he ran a disorganized campaign, raised little money and did not capitalize on his endorsement from Trump, analysts said.
Republicans fear that Kobach could again prevail in a crowded primary field of at least four - with more who may jump in - and then lose the general for the Senate seat.
"Kansas is a liability Republicans don't need and can't afford," said Stewart Boss, spokesman for the Democratic Senatorial Campaign Committee. "McConnell is panicking at the prospect of losing a state he thought he could take for granted."
On Tuesday, McConnell told reporters he felt that Pompeo made the right decision to stay in his current job, given world events, but said that did not mean Kansas would be electing a Democratic senator for the first time since 1932.
Pompeo could still change his mind, as the filing deadline isn't until June 1.
Kobach has vowed to "lead the charge" against illegal immigration and socialism. He sponsored a state law that required voters to provide proof of citizenship, a measure that was overturned by the courts.
He brushed aside the notion that he's not the favored candidate of McConnell and the Washington establishment - or what he called "the D.C. sort of insider armchair quarterbacking of races in the Midwest."
"I think McConnell would prefer someone more malleable, to do what the Senate leadership wants him to do," he said. "I don't take it personally."
An internal NRSC poll published by the Wall Street Journal last year showed Kobach leading a Republican primary field without Pompeo by 43%, far ahead of his closest rival, Rep. Roger Marshall, at 24%. But the party leadership remains wary.
"There is widespread consensus that a Kobach nomination puts the seat in real jeopardy in November," said one Republican strategist, who spoke on the condition of anonymity for fear of offending fellow Republicans. "Kobach has done nothing to show us that he has learned from his past mistakes and, as the national map becomes more competitive, he is a risk we can't afford to take. There will be a full-throttled effort to stop him - the only question is: Which primary candidate does that benefit the most?"
Marshall, 59, an obstetrician from Western Kansas who has been in Congress since 2016, has raised more money than any other candidate in the race, nearly $2 million, including $250,000 in three days last week. He has emphasized his conservative, antiabortion bona fides in campaign ads, saying he has voted with the Trump agenda 98% of the time.
Marshall said he met with McConnell on Jan. 7.
"There is an atmosphere of excitement around here. My phone is blowing up - in a good way," he said. He said that his meeting with McConnell was "phenomenal" and that the leader counseled him to "keep your head down, work hard and go raise money."
Although Kansans have a history of electing moderate and Democratic governors - Kathleen Sebelius was elected to two terms in the 2000s before she became President Barack Obama's secretary of health and human services - the Senate seat will be far more difficult, analysts say.
Even Kelly has said Kansas is not experiencing a "blue wave," but rather a "wave of common sense."
"We're a generally Republican state that generally elects Republicans to statewide office," said Patrick Miller, a political science professor at the University of Kansas. "There is not going to be a radical shift here. We're not going to be a purple state all of a sudden."
Bollier left the Republican Party just over a year ago, shortly before she announced her Senate bid as a Democrat. She had differed with the GOP on gay and transgender rights, abortion and Medicaid expansion.
"I got to the point where I thought: This is just not working. I have to do something different," Bollier said. She now says her Republican roots will better serve her efforts to forge consensus on both sides of the aisle.
Kobach said that Kansas voters may have gone blue in his last race in part because of anti-Trump sentiment. But they'll be focused on the economy and immigration and angry about impeachment proceedings, he said, and not inclined to vote for a Democrat.
"I don't foresee a blue wave in Kansas in 2020," he said.
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