Howard Schultz, Starbucks Corp's outspoken CEO, on Monday urged fellow business leaders to ratchet up the pressure on U.S. political leaders to end the stalemate that has partially shut down the federal government since last week.

"This weekend I heard from several business leaders who shared their concern about our relative silence and impact in urging the political leadership to act on behalf of the citizenry," Schultz wrote in a letter posted on the company's website. "It is our responsibility to address the crisis of confidence that is needlessly being set in motion."

Starbucks released the letter after Schultz sent it to top business executives, whom the company did not name.

Schultz, who was not available for further comment, said he was "utterly disappointed by the level of irresponsibility and dysfunction we are witness to with our elected political leadership."

Since leading the world's biggest coffee chain through a painful but successful restructuring a few years ago, Schultz has waded into several hot-button national debates.

During the battle over raising the debt ceiling in August 2011, Schultz made headlines by calling for Americans to stop making political contributions until lawmakers struck a bipartisan deal on the country's debt, revenue and spending.

Just last month Schultz wrote an open letter to Starbucks customers, asking them voluntarily to stop bringing their firearms into its stores. The company's long-standing policy had been to default to local gun laws, including "open carry" regulations that allow licensed gun owners to wear their weapons in public. Schultz's call followed a series of mass shootings across the country that have fanned a fractious national debate over gun rights.

The deeply polarized U.S. Congress on Monday appeared no closer to finding a political solution to end the government shutdown than when it began last Tuesday, raising concerns about the economic consequences of a prolonged stalemate.

"I don't pretend that both parties are equally to blame for this crisis. But I do think they are equally responsible for leading us to a solution," Schultz said in the letter.

Schultz, a registered Democrat, has not donated to political campaigns since he called for the contribution boycott two years ago, a Starbucks spokesman said.

"We have to do what we can to mitigate and avoid the unintended consequences that the current political direction is leading the country and world toward," Schultz wrote.

Schultz's letter follows an unsuccessful attempt in September by U.S. executives who belong to a group called "Fix the Debt" to persuade lawmakers to avert another standoff and to raise the U.S. borrowing limit.

Starbucks, which has nearly 7,000 company-operated U.S. stores, is planning "actions" to galvanize its large base of customers, the letter said without being more specific.

Late last December, the company used its ubiquitous coffee cups to urge Washington politicians to "come together" and find a deal to avoid going over a "fiscal cliff" of automatic tax hikes and government spending cuts.

Workers wrote the words "come together" on the cups they served to customers, aiming to push President Barack Obama and federal lawmakers to revive budget and tax negotiations that collapsed before the holiday recess.

Starbucks backed the initiative with national "Come Together" ads in The Washington Post and The New York Times. It said millions of cups were signed as part of the action.