SAN JUAN, Puerto Rico -- Though he apologized repeatedly Monday morning for his lack of Spanish skills, Bernie Sanders told an audience in Puerto Rico, “If elected president of the United States, you will have an ally in the Oval Office.”

During a packed day of campaigning on the island before the Democratic primary there in three weeks, Sanders barely mentioned his rival Hillary Clinton. Instead, he tailored his core message about Wall Street “greed” to apply specifically to the debt crisis in the territory.

Puerto Rico defaulted on millions in debt payments this month and will likely default on more unless Congress acts soon.

Last year -- and again this month -- Puerto Rico missed a series of bond payments and has defaulted on previous debt obligations.

“I’m not going to lower the standard of living of the people in Puerto Rico, so that billionaires can have more profits,” he said at a Monday evening rally. "It is unacceptable that venture capitalists are buying Puerto Rican bonds at a fraction what they cost and they expect 100 cents on the dollar. Together we will not allow that to happen.”

For a politician who has been reticent to tailor his message to appease differing constituencies, the senator ticked through a number of policy proposals and political hot-button issues for Puerto Rican residents during his visit.

Sanders argued against any austerity measures proposed as a part of the island’s budget issues. “Austerity will not solve this crisis. We must vigorously oppose all efforts at austerity,” he said. “In the midst of this massive human crisis, it is morally unacceptable that billionaire hedge fund managers have been calling for even more austerity in Puerto Rico.”

He called for an independent audit of the island's debt and for the U.S. Federal Reserve System to use its emergency authority and allow for Puerto Rico to restructure its debt through bankruptcy court.

As for those bedrock proposals of his, such as a Medicare-for-all health care system and free public college tuition, Sanders told the crowd that he intended to expand those benefits to the territory as well. He also talked extensively about growing the renewable energy sector and cutting Puerto Rico’s dependence on fossil fuels.

“His environmental platform is so much more eco-friendly than that of Republicans and also his opponent, Hillary Clinton,” 31-year-old Wilson Santiago, a Ph.D. student here, told ABC News.

Sanders used strong language to describe the U.S. relationship with the territory and vowed to increase the island’s political autonomy. “The people of the United States cannot continue a colonial-type relationship with the people of Puerto Rico,” he said during the morning event.

He promised to bring a “binding” referendum during his first year in office, wherein the people of Puerto Rico would decide their own political status.

“Some people I know want statehood, some people want independence, some people want something else. But that is a decision to be made by the decision of Puerto Rico,” he said during a town hall event at an elementary school in Monday afternoon.

He also called for the release of a famed Puerto Rican nationalist, Oscar López Rivera, who is still imprisoned in the United States.

As has been the case throughout his campaign, Sanders drew impressive crowds, even here. During an evening rally at the University of Puerto Rico Rio Piedras, an additional 3,000 fans waited outside in the dark, after the large theater reached capacity.

Sanders promised to send backup supplies, but conceded then, and later in the day, that he faced an uphill battle because his opponent was so well known on the island.

One man, Gabriel Coss, greeted Sanders at the campaign field office and said he had been volunteering for a month.

“We believe in the political revolution,” Coss said. “But we have no resources in Puerto Rico; we have been working very hard with nothing.”