Biden's ancestral home hopes his win may be 'a positive for Ireland.' London fears it will.

BALLINA, Ireland — Some 3,000 miles east of Delaware, nestled inland from Ireland's wild Atlantic coast, lies the small town of Ballina, the ancestral home of President-elect Joe Biden.

Since his projected win, the close-knit town of 10,000 people in County Mayo has erupted in joy over the success of the man they claim as their own.

American flags fly on street corners, a large painted Biden mural overlooks the town square, while photographs of a beaming Biden hang proudly in shop windows, with slogans that read: "Our man in the White House."

Biden is among some 32 million Americans with Irish heritage, according to U.S. Census Bureau data.

In 2016, he brought his children and grandchildren on an official trip to Ireland to learn about their roots, which also includes family on the east coast in County Louth.

Biden's maternal great-great-great-grandfather Edward Blewitt grew up in the market town of Ballina, known for salmon fishing and for being the birthplace of Ireland's first female president, Mary Robinson. Blewitt emigrated after the Irish Potato Famine of the 1840s to Biden's birthplace of Scranton, Pennsylvania, now a sister city of Ballina.

One member of the town in particular, Joe Blewitt, 41, a plumber and Biden's third cousin, is bursting with pride.

"It's fantastic to see him getting over the line, you know, and so many people voted for him," Blewitt told NBC News.

He has met Biden in Ballina and as a guest at the White House in 2017, when President Barack Obama surprised Biden with the Presidential Medal of Freedom.

"He's a really honorable guy, he's really decent," Blewitt said. "He's a great man for America ... And you know, he's one of our own."

Blewitt's sister, Laurita, was invited by the former vice president onto the campaign trail earlier this year. She said Biden was "so proud of his Irish connection."

She added that she had spoken to Biden's family just after his projected win and is keen to attend his inauguration in January, if coronavirus travel restrictions allow.

But Biden's Irish roots, although a boon for Ballina, may be causing some in London to bristle.

Despite British Prime Minister Boris Johnson last Tuesday being one of the first global leaders to receive a call from Biden, the president-elect has previously stressed the importance of protecting Northern Ireland's peace deal in the Brexit process.

Irish Prime Minister Micheál Martin told NBC News that Biden "may be a catalyst" for resetting relations between Britain and the European Union and said his "commitment to the Good Friday agreement," would be "a positive for Ireland."

The landmark 1998 peace deal effectively ended 30 years of sectarian violence in Northern Ireland and created new institutions for cross-border cooperation.

Then-President Bill Clinton played a central role in brokering the deal, dragging staunchly opposing sides to the negotiating table, helping end decades of political deadlock and fighting.

After an acrimonious referendum campaign in 2016, Britons voted to leave the E.U. After officially leaving in January this year, Johnson's government is now in the midst of negotiating a trade deal with the bloc.

But because of frustrations with that process, Johnson has put forward legislation that he acknowledged could violate international law and break the Northern Ireland protocol of the Brexit divorce treaty.

That prompted alarm and a warning two months ago from Biden who has repeatedly said the U.S.-brokered peace deal must not be undermined or become a "casualty of Brexit." Biden has cautioned London to honor the 1998 agreement or there could be no separate post-Brexit U.S. trade deal, which Westminster craves.

Without mentioning Brexit, Johnson welcomed Biden's win, tweeting after their phone call: "I look forward to strengthening the partnership between our countries and to working with him on our shared priorities."

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Britain has said it is willing to leave without a E.U. trade deal — despite many businesses warning this could cause chaos — which could further complicate the sensitive border of Northern Ireland, which is part of the United Kingdom, with Ireland, which is part of the bloc.

To add to the pressure, the clock is ticking. The deadline for a trade deal is scheduled for Dec. 31.

Irish Foreign Minister Simon Coveney said Wednesday that Biden was undoubtedly "both emotionally and politically" close to Ireland.

"Joe Biden understands the complexity of Irish politics north and south, the complexity of the Irish relationship with the U.K.," he said.

Meanwhile, Martin was among the first world leaders to congratulate Biden on his success and said he had already invited the president-elect to visit the country once he's in office.

"It's a moment of celebration at an emotional level," Martin said. "There is that sense of one of our own has made it to the top of the United States."

Reuters contributed to this report.