WASHINGTON - Republicans in the U.S. Congress faced growing blowback on Monday from businesses that said they would cut off campaign contributions to those who voted last week to challenge President-elect Joe Biden's victory.

The announcements by Amazon.com Inc, General Electric Co, Dow Inc, AT&T Inc, Comcast Corp, Verizon Communications Inc, American Express Co, Airbnb Inc, Cisco Systems Inc, Best Buy Co Inc and Mastercard Inc, among others, threaten to throttle fundraising resources for Republicans who will soon be out of power in the White House and both chambers of Congress.

AT&T and Comcast, for example, are among the biggest corporate donors in Washington.

Greeting-card giant Hallmark Company Ltd said it had asked senators Josh Hawley and Roger Marshall to return its contributions. Representatives for the two Republicans, who both objected to Biden's certification, did not immediately respond to requests for comment.

The announcements are a sign that some corporate donors, which typically spread their money widely around Capitol Hill, are re-assessing their strategy after supporters of President Donald Trump attacked the Capitol last week in an effort to prevent Congress from formalizing Biden's victory. 

It is unclear whether their decisions will have a lasting impact. Fundraising activity is currently at a post-election lull in Washington, giving businesses and trade groups some time to figure out their approach.

Few companies have gone as far as Dow Inc, which said it would withhold donations for the Republican lawmakers' entire terms in office - up to six years for those in the Senate. Others said they would withhold donations temporarily, or suspend giving to Republicans and Democrats alike.

GE's suspension will last through the end of 2022 and then the employee board that oversees its political action committee will consider requests for support for those lawmakers who opposed certification "on a case-by-case basis."

At least five people died in last week's attack, which also forced lawmakers into hiding for several hours.

When they reconvened, 147 Republicans in the House of Representatives and the Senate voted to challenge Biden's victory in Pennsylvania or Arizona, even though both states already formally certified the results and election officials say there were no significant problems with the vote.

Those voting yes included the top two House Republicans, Kevin McCarthy and Steve Scalise, and Senator Rick Scott, who as incoming head of the National Republican Senatorial Committee will head efforts to win back the Senate in the 2022 elections. All of their jobs require extensive fundraising. McCarthy and Scalise's offices did not respond to a request for comment. Representatives for Scott declined to comment.

Amazon said it would discuss concerns "directly with those members we have previously supported" before deciding whether to resume contributions.

CUT OFF FOR HOW LONG

The sheer extent of the Republican opposition will make it difficult for businesses to simply cut off those who voted against certifying Biden's victory, said a senior Republican business strategist, speaking on condition of anonymity. Roughly two-thirds of all House Republicans, including seasoned legislators and vocal Trump partisans, supported the challenge.

Business groups will be watching closely over the coming weeks to see whether those Republicans make gestures to re-establish a sense of normalcy, such as attending Biden's inauguration, the strategist said.

"Each of those people are going to be scrutinized," the strategist said. "Are they all going into the bucket of 'no contributions' I would be shocked if they all get put in."

A growing list of companies, including

Copper giant Freeport-McMoRan Inc, Ford Motor Co, Microsoft Corp, American Airlines, Alphabet Inc's Google, Facebook Inc, Goldman Sachs, BP Plc, Smithfield Foods Inc and Union Pacific Corp said they would temporarily suspend donations to Democrats and Republicans alike.

Late Monday, Northrop Grumman became the first major defense contractor to temporarily halt all donations. "We are pausing political action committee giving and evaluating the way forward,” a spokesman said.

Trade associations, among the biggest donors in Washington, are moving more slowly.

The National Association of Beer Wholesalers, the National Association of Auto Dealers, and the American Bankers Association said they would re-assess their contribution strategy. Other top donors, including the National Association of Homebuilders and the National Association of Realtors, said they have yet to make a decision.

Several analysts said the boycott may not be permanent, as the need for access on Capitol Hill might ultimately outweigh the risk of being seen as an underwriter of those who weaken U.S. democracy.

"It’s very easy to suspend campaign contributions two months after an election. The question is whether these policies will remain in effect," said Stanford University law professor Nathaniel Persily.

(Reporting by Andy Sullivan and David Shepardson in Washington Additional reporting by Jessica DiNapoli, Karen Freifeld, Ross Kerber, Linda So, Tom Polansek, Diane Bartz, Matthew Scuffham, Paresh Dave, Mike Stone, Jessica Resnick-Ault, Ernest Scheyder, Brad Heath and Nandita Bose Editing by Andrea Ricci, Matthew Lewis and Raju Gopalakrishnan) ((andy.sullivan@thomsonreuters.com; +1 202 421 5603; @andysullivan))