Roelof Botha arrived last week at the annual Allen & Company conference in Sun Valley, Idaho, to meet and mingle with tech and media moguls. A controversy brewing back home followed him to the exclusive retreat.

Mr. Botha, the managing partner of Sequoia Capital, a storied Silicon Valley venture capital firm, was repeatedly asked at the event about a colleague, Shaun Maguire, two people with knowledge of the matter said. Mr. Maguire — perhaps Sequoia’s most outspoken partner — had posted on X on July 4 that Zohran Mamdani, the progressive Democrat running for New York City mayor, came from a “culture that lies about everything” and was lying to advance “his Islamist agenda.”

Mr. Maguire’s post was immediately condemned across social media as Islamophobic. More than 1,000 technologists signed an open letter calling for him to be disciplined. Investors, founders and technologists have sent messages to the firm’s partners about Mr. Maguire’s behavior. His critics have continued pressuring Sequoia to deal with what they see as hate speech and other invective, while his supporters have said Mr. Maguire has the right to free speech.

In Sun Valley, Mr. Botha listened, but remained neutral, the people with knowledge of the matter said.

For half a century, Sequoia has tried to maintain that neutrality, even as rival venture capital firms such as Andreessen Horowitz and Founders Fund started taking political stances. But as Mr. Maguire has increasingly made inflammatory comments, including saying that diversity, equity and inclusion “kills people,” Sequoia is now in a place that its leaders never wanted to be: smack in the middle of the culture wars.

It’s a tricky moment for the vaunted venture firm, which backed Apple, Nvidia and Google when they were start-ups. For decades, Sequoia kept its partners in the background while shining the spotlight on the founders of the start-ups it invests in. Yet those values have become harder to adhere to as the venture industry has ballooned, and many investors have cast off traditions.

While Mr. Maguire is unusual at Sequoia for his outspokenness on X, he is not an industry outlier. Venture capitalists such as Marc Andreessen and Peter Thiel have openly talked about their thinking, sometimes with the intent of influencing national politics.

Publicly, Sequoia has said nothing about Mr. Maguire. Behind the scenes, one senior partner at Sequoia, Doug Leone, appeared to defend Mr. Maguire, according to email correspondence reviewed by The New York Times.

“Sequoia is backed into a corner and only has bad options,” said Paul Biggar, the chief executive of the advocacy group Tech for Palestine, who also founded CircleCI, a software development start-up. “People are speaking up because everyone sees what they’ve supported, and directionally that’s only going to get worse for them.”

Sequoia declined to comment. In an interview with Fortune in March, Mr. Botha described the firm as having a “spirit of institutional neutrality” while allowing individuals to hold their political differences.

In a nearly 30-minute video posted on X last week, Mr. Maguire again called Mr. Mamdani “an Islamist,” and a “wolf in sheep’s clothing.” Mr. Maguire also tried drawing a distinction, saying “Islamists are not all Muslims” and apologized “to any Muslim that is not an Islamist and to any Indian that took offense with this tweet.”

Mr. Mamdani’s campaign did not respond to a request for comment.

Founded in 1972, Sequoia was known for years for its stellar track record with investing in start-ups. The firm reaped billions of dollars when young companies that it bet on burgeoned into large businesses and went public or were acquired for enormous sums.

By the 1990s, Sequoia had established itself as a top venture firm on Sand Hill Road in Menlo Park, Calif., with investments in companies like Cisco, the telecommunications hardware provider. It also invested in PayPal, YouTube, Instagram, WhatsApp and Zoom, among others. For start-ups, Sequoia’s stamp of approval meant they were a player.

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Throughout, Sequoia’s partners tried to stay out of the limelight. But over time, more investors arrived in Silicon Valley seeking start-ups that would blossom into the next Google or Airbnb. To stand out, some venture capitalists at firms like Andreessen Horowitz and Founders Fund started blogging and posting on social media, aiming to be thought leaders. Talking about third-rail political issues became more common.

In 2016, Michael Moritz, a senior partner at Sequoia and the firm’s most prominent Democrat, penned an editorial in The Financial Times criticizing Donald J. Trump. In 2020, Mr. Leone, a Republican, donated to the re-election campaign of Mr. Trump, but denounced the president in a statement to the press after the Jan. 6, 2021, uprising at the Capitol.

Those moments, along with similar ones over the years, paved the way for others at Sequoia to speak more openly about their politics, two people with knowledge of the firm said.

Sequoia hired Mr. Maguire, 39, who co-founded a cybersecurity company, in 2019 on the recommendation of Patrick Collison, the chief executive of Stripe, a payments start-up that is one of the venture firm’s largest investments. Mr. Maguire had chafed at hot-button issues before; he once claimed he was not promoted at another venture firm for “being a white man.”

At Sequoia, Mr. Maguire tied himself to Elon Musk. Mr. Maguire helped land the firm its investment in SpaceX, Mr. Musk’s rocket company, which has soared in value. Mr. Maguire also led Sequoia’s deals with other companies run by Mr. Musk, including the tunneling firm the Boring Company, the social media platform X and the artificial intelligence start-up xAI.

People who know Mr. Maguire described him as warm and friendly in person and said his relative youth — Mr. Botha, by contrast, is 51 — made him relatable to younger entrepreneurs.

But Mr. Maguire also developed a reputation — or perhaps notoriety — as a prolific user of X, where he has more than 275,000 followers. In dozens of posts daily, he has commented on political issues and progressive causes. After Hamas attacked Israel on Oct. 7, 2023, Mr. Maguire, who is a self-described “Jew and a Zionist,” defended the Israeli government’s response while raising alarms on what he saw as a rise in antisemitism.

“With every single person I meet, the first thing through my brain is: ‘would they want to kill me if they knew I was Jewish?’” he posted on X three days after the attack.

Silicon Valley noticed. Founders, investors and other tech workers messaged Sequoia’s partners and other employees about Mr. Maguire’s behavior, two people familiar with the matter said.

This month, Mr. Maguire posted about Mr. Mamdani after The Times published an article about how the mayoral candidate, a Muslim of South Asian descent who was born in Uganda, wrote that he was Asian and African American in an application to Columbia University. (He was not admitted to the school.) Mr. Mamdani had just won New York City’s Democratic mayoral primary on a progressive platform, emphasizing affordability and other cost-of-living issues, and had defended the rights of Palestinians.

In response to Mr. Maguire’s post, technologists and start-up founders circulated the open letter calling for Sequoia to commission an independent investigation into his behavior. The letter claimed to represent roughly 1,000 start-ups, with signatures from more than 1,100 people, though not all the names on the list could be verified. At least one company that signed the letter was funded by Sequoia.

“This was not a misstep,” the letter said of Mr. Maguire. “It was a deliberate, inflammatory attack that promotes dangerous anti-Muslim stereotypes and stokes division.”

In a post on X, Mr. Maguire referred to his “enemies” and said, “I’m going to play nice for now, but am ready to embarrass any of you should you escalate.”

A counterletter supporting Mr. Maguire garnered more than 1,000 signatories, including Bill Ackman, a billionaire financier who supports Israel, as well as start-up founders whose companies are backed by Sequoia. The letter described Mr. Maguire as a “principled thinker” who has “helped build careers, fund companies and elevate voices across divides.”

Others have sent private messages to Sequoia employees urging them to stand by Mr. Maguire, two people with knowledge of the matter said.

Sequoia insiders have trod carefully. On July 10, Pat Grady, a partner at the firm, posted a statement on X sympathizing with both the Muslim community and Mr. Maguire. It was reposted by Alfred Lin, another partner.

“I do not agree with everything my partners say,” Mr. Grady wrote. “Aggressive truth-seeking and a healthy conflict of ideas is a hallmark of Sequoia. These are key ingredients in making the partnership great.”

In emails with a concerned founder this month, which were reviewed by The Times, Mr. Leone wrote that Mr. Maguire’s posts did not condemn Muslims. Mr. Leone also echoed a point Mr. Maguire has made publicly, distinguishing between “Islamists” and “Muslims.”

On Monday, the signatories who called for Mr. Maguire to be disciplined asked that tech workers reach out to Sequoia’s financial backers and clients — including the University of Michigan, Duke University and the University of Texas system — to speak with the firm.

“If we, the global technology industry, are serious about building a more inclusive future, it starts with holding power accountable,” the letter said.