By David Morgan and Jarrett Renshaw
(Reuters) - Kentucky Democrat Amy McGrath's long-shot bid to unseat U.S. Senate Majority Leader Mitch McConnell could help undermine Republican efforts to retain their majority in the chamber, even if the former Marine Corps fighter pilot fails to beat McConnell in November.
Political analysts see the chances of Democrats winning enough seats to seize control of the Senate in the Nov. 3 U.S. election rising, with President Donald Trump's sliding poll numbers endangering a growing number of Republican incumbents.
McConnell, a tenacious political survivor, has endured election challenges in the past and is still expected to defeat McGrath, who on Tuesday emerged as her party's nominee to challenge him.
But McGrath has raised more campaign funds than McConnell and poses a threat. That means the Republican Party and Republican-aligned political action committees may be forced to spend more to bolster McConnell's re-election bid than they may have planned, potentially limiting resources that could go to help incumbents in eight other states who are seen as vulnerable, analysts and officials from both parties said.
"It's a very precarious situation for Republicans. There are multiple paths to a Democratic majority, and those increase with the president's national polling numbers on the decline," said Jessica Taylor, a political analyst who tracks Senate races for the nonpartisan Cook Political Report.
Republicans hold 53 of the Senate's 100 seats. With Democrats controlling the House of Representatives, Republican control of the Senate has been crucial in buttressing Trump's presidency including keeping him in power after a February impeachment trial.
Twenty-three Republican incumbents are seeking re-election this year, compared to 12 Democratic incumbents. Senators serve six-term terms.
One vulnerable Republican is Thom Tillis, a North Carolina freshman who polls show trailing Democratic challenger Cal Cunningham in a Senate race that Republican officials expect to shatter national spending records.
"This is going to be one of those bloodbath elections and money is going to play a big role. If resources are being unexpectedly diverted to other races, that could be a problem for Tillis," a North Carolina Republican operative said, speaking on condition of anonymity.
More than $100 million in television ads have already been booked for the fall in North Carolina, according to a North Carolina Republican official familiar with the spending plans.
McGrath has become a magnet for contributions from Democratic donors and activists who desperately want to oust McConnell, according to analysts and party officials. Her campaign raised more than $41 million as of June 3 - the latest available figure - compared to $27 million for McConnell.
Republicans said McGrath was forced to divert much of her war chest to fend off a powerful primary challenge from Democrat Charles Booker, a Black state legislator.
"No candidate has spent so much to achieve so little," McConnell campaign press secretary Katharine Cooksey said of McGrath.
POLITICAL ACTION COMMITTEES
McConnell has received no funds from official Republican Party campaign committees. But political action committees - entities that raise and distribute campaign funds - aligned with Senate Republicans and other party figures have more than doubled their contributions to McConnell this year, compared to his last re-election bid in 2014.
McConnell has received about $385,000 from such Republican PACs as of June 3, compared with $178,000 over the same period in 2014, according to Federal Election Commission records. The current figure is approaching 2014's $404,000 total, according to the Center for Responsive Politics, which tracks campaign spending.
The Senate Leadership Fund, a McConnell-aligned PAC, has set aside $10.8 million for fall campaign television ads backing him. Larger sums have been reserved for only two other Republican senators, including Tillis, who can expect $21.8 million.
Republicans face a deepening challenge nationwide as Trump loses support among suburban voters, older voters and other key voting blocs, according to opinion polls, during the tumult of the coronavirus pandemic and protests over racism and police brutality.
Democrats would need a net gain of four Republican-held seats to take control of the Senate if Trump wins re-election - or three if Democratic candidate Joe Biden defeats Trump.
Republican seats in the Senate are considered vulnerable in at least eight states: Arizona, Colorado, Georgia, Iowa, Kansas Maine, Montana and North Carolina. Democrats are at risk in at least two: Alabama and Michigan.
For example, Republican Senator Joni Ernst narrowly trails her Democratic challenger, Theresa Greenfield, in Iowa, a state Trump carried by 9 percentage points in 2016. Ernst, who has $12.6 million set aside for her at the Senate Leadership Fund, privately told supporters that Trump's unpopularity with suburban women is weighing her down, two sources familiar with the conversations said.
"If they are spending a ton in Iowa close to the election," said one Iowa GOP operative, "then it's real bad for every Republican."
(Reporting by David Morgan in Washington and Jarret Renshaw in Philadelphia; Editing by Scott Malone and Will Dunham)