LAS VEGAS/WASHINGTON, July 18 (Reuters) - U.S. President

Joe Biden's campaign is pursuing a razor-thin path to reelection

against his Republican opponent Donald Trump in November, senior

Democratic officials say, with four of the seven key

battleground states now looking increasingly out of reach.

Georgia, Arizona and Nevada - all claimed by Biden in

2020 - in addition to North Carolina which Democrats had hoped

at one point to take back from Trump have grown more

challenging, more than a dozen campaign officials and senior

Democrats in battleground states told Reuters in interviews.

Trump, 78, had been leading the polls in all four states

well before he was grazed by a bullet last weekend, a position

that consolidated after Biden's disastrous debate performance on

June 27.

Calculations can change before election day. But the

campaign officials' latest assessment allows for almost no

margin of error. Biden, 81, can only cobble together the 270

Electoral College votes needed to clinch the presidency if he

wins the Rust Belt manufacturing states of Pennsylvania,

Wisconsin and Michigan and a congressional district in Nebraska

that could also soon be at risk.

"It's looking very tight" in Arizona, Georgia and Nevada, a

senior campaign official told Reuters. "Michigan, Pennsylvania,

Wisconsin is the clearest path to 270. That is what we're

focusing on."

However, Dan Kanninen, the director for battleground states,

said the campaign was adding staff in Arizona and Nevada and

that being "highly competitive" in all of the swing states

remained a priority. "I do not see the map narrowing for us," he

said in an interview.

Biden was on the second day of a two-day trip to Nevada on

Wednesday, when the White House announced he had a mild case of

COVID and had canceled a planned speech.

Democratic lawmakers have voiced fears that Biden would

lose not only the White House but also the House of

Representatives and Senate to the Republican party.

The campaign had hoped those voices would quiet after the

shooting. But U.S. Representative Adam Schiff, a California

Democrat who is running for the Senate, warned donors in a

private meeting Tuesday that the party was likely to suffer

major losses if Biden continued to run.

Trump's immediate, televised reaction to the shooting -

a raised fist as blood streamed down his face from a grazed ear

- contrasted with questions over Biden's mental acuity and

whether he has the stamina for four more years in the White

House.

Although most polls show Biden lagging Trump in the Rust

Belt states the campaign is focused on, the Democratic candidate

remains "within the margin of error," the senior official noted.

"This is the strongest path, one we're focused on right

now," the official added.

The narrowing map for Biden means a widening one for Trump.

Some polls before the shooting showed Trump competitive in

Democratic-leaning Virginia, New Hampshire and even Minnesota,

which hasn't supported a Republican presidential candidate since

1972.

"When things go south, they go south everywhere," James

Carville, a veteran Democratic strategist, said. "This has been

the worst summer for a national party since Republicans and

Watergate," he added, referring to the Congressional

investigation that resulted in Republican President Richard

Nixon's resignation in 1974.

'BEST CASE' COULD JUST EKE OUT A WIN

Biden beat Trump in 2020 in the popular vote by seven

million votes and racked up 306 votes in the electoral college

to Trump's 232, with support from suburbs and the well-to-do in

the Rust Belt states and the Sun Belt of Arizona and Nevada, as

well as a rush of young voters after a summer of protests for

racial justice and civil rights.

Since the November 2020 election, Biden pumped federal money

into infrastructure and manufacturing, while overseeing a

post-COVID economy that grew faster than other nations, but hit

inflation highs. His support for Israel's assault on Gaza after

the attacks by Hamas, which have killed over 37,000

Palestinians, has splintered the coalition that elected him.

Battleground state polls have favored Trump for months, and

particularly since the debate in which Biden stumbled and

struggled to complete sentences, while Trump repeated a series

of well-worn falsehoods. None have been published since the

shooting, but the assassination attempt has increased enthusiasm

for Trump among his fans, which could boost Republican turnout.

Biden "would have to draw an inside straight without missing

a single potential electoral vote in order to just scrape over

the finish line of 270," said Republican pollster Whit Ayres,

referring to a tough poker hand.

U.S. presidential elections in recent years have been

decided by a narrow slice of voters in a handful of states, but

the new map for Biden - if successful - would eke out a victory

with just 270 electoral college votes to Trump's 268, the

narrowest victory since Republican Rutherford B. Hayes won by

one electoral college vote in 1876.

Nebraska is one of two states which splits their electoral

college votes. (Maine is the other).

Biden won the congressional district which includes Omaha in

2020, but Republicans, who are in control of the state, are

expected to hold a special session later this month to make

Nebraska a winner-take-all election. That would block Biden from

a single, clinching electoral vote - and could create an

unprecedented 269-269 tie vote.

'POLL-ERCOASTER'

While some Democrats see a narrower map, many strategists

and state party officials say they remain optimistic about wider

wins against Trump.

Since 2020, they point out, Trump and his allies sued

unsuccessfully to overturn the election results; his followers

attacked the U.S. Capitol on Jan. 6, 2021; a jury found him

guilty of sexual abuse and he was convicted of multiple felonies

over hush payment to a porn star.

"They're not any independent Democratic voters who looked at

Donald Trump get shot in the ear and say, 'Oh my god, I gotta

vote for this guy,'" said Bakari Sellers, a Democratic political

analyst. "There's no such thing as a sympathy vote in the United

States of America."

The campaign is spending $50 million on paid media in

battleground states in July, and by the end of the summer those

states will have more than 2,000 staffers, officials said.

Democrats had hoped earlier this year that the party could

flip North Carolina, which has backed only one Democrat for

president since 1976. Biden and Vice President Kamala Harris

have visited multiple times, the campaign spent millions on

hiring and advertising, and Anderson Clayton, the 26-year-old

Democratic party chair there, has spent the year knocking on

doors.

The campaign isn't counting the state out, Clayton said.

"I don't ride a 'poll-ercoaster', and I think that, you

know, the investments on the ground would say that North

Carolina is being prioritized just as much as we need it to be

this year in order to, I think, put it on the map."

She added: "I feel like sometimes people that are so

engaged in the bubble oftentimes forget to touch grass every

once in a while."