U.S. Sen. Martin Heinrich (D-N.M.) and Rep. Darren Soto (D-Fla.) announced Tuesday they would introduce legislation to start the motions for Puerto Rico statehood.

Why it matters: More than 52% ofPuerto Ricans voted last November in favor of statehood, three years after Hurricane Maria struck the island and caused one of the worst natural disasters in recorded history. It exposed the island's vulnerable position as a U.S. territory and its lack of resources to battle poverty.

• The 3.2 million Americans in Puerto Rico lack full voting representation in Congress and cannot vote for president.
• Statehood proponents say the federal government treats Puerto Rico unequally and doesn't adequately fund programs to combat poverty and promote economic development.

The details: Under the proposal, also supported by Puerto Rico's nonvoting member in the U.S. House, Jenniffer González-Colón (R-Puerto Rico), Congress would provide Puerto Rico a formal offer to became the 51st state.

• The legislation outlines the process for Puerto Rico's admission into the U.S, should it be ratified by Puerto Rico voters in a federally-sponsored, yes-or-no referendum.
• The plan sets a timeline for the future referendum vote, declaration of Puerto Rican statehood, and an election for the Puerto Rican Congressional Delegation.
• The outline is similar to the one set for Alaska and Hawaii in their quests for statehood.

What they're saying: "My home state of New Mexico had a similar struggle to achieve statehood. It took 50 New Mexico statehood bills and 64 years before we were finally admitted to the United States," Heinrich said.

• Heinrich is the senior senator in the nation's most Hispanic state and, in recent years, has been aligning himself with issues supported by many Latinos.
• Puerto Rico Gov. Pedro Pierluisi told Axios' Alexi McCammond that he had been in contact with Heinrich on a Puerto Rican statehood proposal.
• New Mexico is home to 2 million people, 2 U.S. Senators, and three members of the U.S. House of Representatives. Puerto Rico's population is 63% larger.

Yes, but: GOP leaders have resisted moves to allow Puerto Rico and the District of Columbia to become states.

• Some Republicans claim the move would give Democrats four assured seats in the U.S. Senate — a charge pro-statehood champions in Puerto Rico say is not true since the island has a history of voting for conservative leaders.

What they're saying: "After they change the filibuster, they’re going to admit the District as a state," Senate Majority Leader Mitch McConnell said last September. "They’re going to admit Puerto Rico as a state. That's four new Democratic senators in perpetuity."

The big question: Puerto Rico statehood proponents need to convince some Republicans in the U.S. Senate to support a statehood plan to get a proposal through the divided chamber.

• Should Puerto Rico become a state, the Puerto Rican non-commonwealth population would surge in the U.S. to 9 million.
• They would be the second-largest U.S. Latino group behind Mexican Americans, who are nearly at 37 million.