Kellyanne Conway, a senior aide to President Donald Trump, said Sunday that he has no plans to release his tax returns, a marked shift from Trump's pledge during the campaign to make them public once an audit was completed.

"The White House response is that he's not going to release his tax returns," said Conway, counselor to the president, during an appearance on ABC's This Week With George Stephanopoulos. "We litigated this all through the election.

"People didn't care," Conway added. "They voted for him, and let me make this very clear: Most Americans are very focused on what their tax returns will look like while President Trump is in office, not what his look like."

Presidents are not required to release their tax returns, but presidents dating back to Richard Nixon have routinely voluntarily done so.

A Washington Post-ABC poll last week showed that Trump's continued refusal to release his tax returns continues to be an unpopular decision, with 74 percent of Americans saying he should make the documents public, including 53 percent of Republicans.

Conway was questioned about a petition page on the White House website that allows citizens to ask government officials to take up issues of importance to them. Under former President Barack Obama, the White House would note any actions related to petitions that garnered more than 100,000 signatures online.

As of Sunday morning, a petition for Trump to immediately release his tax returns had received more than 200,000 signatures.

One petition asks the administration to "immediately release Donald Trump's full tax returns" and says it wants Trump to not be in conflict with the emoluments clause of the Constitution.

Less than a day after the petition was started, it eclipsed the 100,000-signature mark — enough to elicit an official response.

The petition says that "unprecedented economic conflicts of this administration need to be visible to the American people."

It seeks documentation about "foreign influences and financial interests which may put Donald Trump in conflict with the emoluments clause of the Constitution."

The clause prohibits a president from accepting a gift or a benefit from a foreign leader. It was drafted by the Founding Fathers to prevent the leaders of the fledgling United States from being under the financial thumb of a foreign country like France or England.

But Trump's critics say the billionaire businessman was violating the Constitution the moment he swore an oath to protect and defend it.

Ron Fein, the legal director at Free Speech for People, told the Washington Post's Matea Gold that there are several examples of Trump violating the emoluments clause, including rent paid by the Industrial & Commercial Bank of China for its space in Trump Tower in New York and spending by foreign diplomats at the Trump properties, including his hotel in Washington, a few blocks from his new home.

Trump has said he would donate profits from foreign business clients to the U.S. Treasury, although he hasn't said how he'd track, collect and disburse such payments, according to Gold.

And even if he's found to be in violation of the emoluments clause, it is unclear whether a violation of it qualifies as "treason, bribery or other high crimes and misdemeanors" that could lead to Trump's impeachment.

Trump's refusal to release his tax returns became a heated issue on the campaign trail.

On Jan. 11, during Trump's first official news conference since winning the election, he continued to resist suggestions to release the returns.

"The only ones that care about my tax returns are the reporters," Trump said. "You learn very little from a tax return."

During the campaign and since then, Democrats consistently criticized Trump for not releasing his returns, saying that information was needed to evaluate conflicts that might be posed by his vast business holdings.

"You know full well that Trump — President Trump and his family are complying with all the ethical rules, everything they need to do to step away from his businesses and be a full-time president," said Conway.

On NBC's Meet the Press on Sunday, Conway said that White House press secretary Sean Spicer had presented "alternative facts" on Saturday when he falsely stated that Trump's swearing-in ceremony drew "the largest audience to ever witness an inauguration."

Spicer made that claim during a late Saturday afternoon briefing, in which he scolded reporters for trying to "lessen the enthusiasm of the inauguration" by deliberately reporting numbers that were lower than the White House believed.

Confronted by Meet the Press host Chuck Todd about Spicer's characterization, Conway responded by saying: "You're saying it's a falsehood, and Sean Spicer, our press secretary, gave alternative facts to that."

Conway later backtracked and said there was no way to know which audience was larger.

"I don't think you can prove those numbers one way or another," she said. " There's no way to quantify crowd numbers."