With the Democrats probably needing only four seats to seize control of the Senate, organizations such as the US Chamber of Commerce are funding key races

With Donald Trump’s campaign still reeling from his lascivious comments about groping women on an 11-year-old tape, a growing number of GOP mega-donors and outside groups are fretting about the Republicans losing their congressional majorities, and scrambling to pour tens of millions more into ads and voter mobilization drives in tight races to stave off Democratic challengers.

The release of Trump’s remarks about assaulting women on Friday and his slash-and-burn attacks on Hillary Clinton and her husband in the second presidential debate, have fueled growing Republican worries about the Democrats taking one or both houses, say GOP donors and former members. If Clinton wins, meaning Vice-President Tim Kaine would hold the casting vote in the Senate, meaning the Democrats would only need to pick up four seats to control the upper chamber. The Republicans currently have 54 Senate seats, and the Democrats 44, along with two independents who caucus with them.

Wisconsin lawmakers urge investigation of Scott Walker after 'John Doe' papers Read more

In two tight Senate contests, Nevada and New Hampshire, GOP candidates on Saturday announced they could no longer stomach Trump, and called on him to withdraw. On Monday, the House speaker, Paul Ryan, fired another salvo at Trump by saying he would no longer campaign for him or defend him, and told members they should feel free to focus on their own survival.

“I think Republicans were feeling pretty good about the Congress a couple weeks ago, but this morning they’re very worried,” former representative Vin Weber told the Guardian on Monday. Weber has helped raise funds for a politically-active non-profit, the American Action Network, and an allied Super Pac, the Congressional Leadership Fund, that are trying to keep the GOP majority. The fund has received $20m from casino mogul Sheldon Adelson.

“Republicans are scared to death of what would happen if they lost the Senate and House, regardless of which candidate” wins the presidency, billionaire broadcaster Stan Hubbard told the Guardian. Hubbard, who has contributed over $100,000 to a pro-Trump Super Pac, added of Trump and Clinton: “They’re both disgusting.”

Hubbard, a major donor to a few conservative groups, said he got a call last week from the US Chamber of Commerce, which is strictly focused on congressional races. Although he had already given a six-figure check to the Chamber of Commerce, Hubbard said he pledged another, somewhat smaller, check after talking to the organization’s top executive, Tom Donohue, about the risks of losing the Senate.

Pence refuses to answer questions on political 'puppetry' and big donations Read more

The Chamber of Commerce is one of a few key outside groups spending big bucks to stave off Democratic Senate challengers in at least six crucial states. Besides Nevada and New Hampshire, the others are Indiana, North Carolina, Missouri and Pennsylvania. Last week the Chamber of Commerce began its fourth ad buy in Nevada, a $1m effort to help representative Joe Heck win the Senate seat of retiring Senator Harry Reid.

Several days after the first debate, the conservative big donor and advocacy network led by the billionaire Koch brothers – which has said it isn’t backing Trump due to strong concerns about his policies and rhetoric – hosted a conference call with donors, asking for at least $10m more for Senate ads and get-out-the-vote efforts which have been its major focus, a donor who was on the call told the Guardian.

The Koch network, which expects to spend about $42m this year on TV and digital ads in eight states, might spend a few million more on “strategic media buys” and voter mobilization drives, said James Davis of Freedom Partners Chamber of Commerce, the financial hub of the sprawling advocacy network. Koch-backed advocacy groups, Davis added, are now “focused on turning out 5 million voters in the eight states”.

The Koch network’s concerns about the Senate were underscored for donors when they received an email, seen by the Guardian, with new poll results in key races, which painted a worrisome picture.

Two other cash-rich outside groups, a Super Pac dubbed the Senate Leadership Fund and an allied non-profit called One Nation, have stepped up their fundraising efforts.

As of 1 September the two groups had raised just under $100m this election cycle, including $42.4m in August. And the Leadership Fund expects to spend close to $75m in seven key states in September and October combined, according to a spokesman. Adelson and his wife have has given the Super Pac $20m and chipped in $10m to the allied non-profit, according to records and fundraising sources.

Other conservative groups and their big donors are worried about losing the Senate. “Victory for us is keeping the Senate and the latest disgusting episode doesn’t help us,” said Michael Epstein of the Republican Jewish Coalition, a staunchly pro-Israel group heavily backed by Adelson. “Trump is a destructive force … He’s hurting the country, the GOP and the Trump brand.”