The speaker of the Massachusetts House has chosen Representative Jeffrey Sánchez to be the chamber’s budget chief, elevating the self-described “practical progressive’’ to one of the most influential positions in state government.

Speaker Robert A. DeLeo’s decision gives the Jamaica Plain Democrat huge sway over taxes, public policy, and how $40 billion in taxpayer money is spent every year.

Sánchez’s promotion will put him in a role that has been used as a steppingstone to the speaker’s office, making him a potential candidate to succeed DeLeo whenever the 67-year-old retires.

After a perfunctory vote of Democratic representatives on Monday formalizing his new role, Sánchez, who turns 48 this week, will arguably be the most powerful Latino elected official in Massachusetts history.

In a joint interview with DeLeo on Sunday at the State House, Sánchez said he comes to the job with great humility and a desire to help the state’s most vulnerable.

“This position allows me an opportunity to continue my work to help the underserved in our Commonwealth,’’ he said. “I’ve devoted my life to making sure that the most challenged have had a voice, and I want to continue that.’’

DeLeo said he picked Sánchez, the current cochairman of the Joint Committee on Health Care Financing, because of his strong legislative record, ability to work with colleagues of all political stripes, and background in health care, which makes up a big chunk of state spending.

DeLeo also said that on a recent visit to Sánchez’s Boston- and Brookline-based district, he saw a man who remained anchored to his constituents.

“What that show[ed] me is a guy who hasn’t forgotten the people that he represents,’’ the Winthrop Democrat said.

While Sánchez was notably short on specifics (he’s brand new to the job and is learning, he said with a laugh), he emphasized that health care would play a big role in the budget discussions during his tenure, as they have for years.

State spending on Medicaid, the health program for the poor and disabled, has skyrocketed — generally outpacing inflation, personal income, and tax-revenue growth. The program eats up an increasingly large portion of the budget pie, constraining the cash available for everything else, from education to support for cities and towns.

In the fiscal year that began July 1, Medicaid will make up 40 percent of the expected expenditures, although the state will be reimbursed by the federal government for perhaps half of those costs.

Asked whether they would be willing to consider reducing benefits or narrowing eligibility for Medicaid to reduce costs, DeLeo and Sánchez demurred. “It’s one of the big issues we have relative to this discussion,’’ the speaker replied.

Sánchez will step into the new role as policy makers grapple to finalize the state budget for this fiscal year, after months of tax revenues having come in far below expectations.

Governor Charlie Baker is expected to announce on Monday his take on the House- and Senate-passed budget.

Among his options: signing it into law, vetoing some spending, and sending portions of the bill back to lawmakers with changes.

The announcement from DeLeo comes after the current chairman of the House Committee on Ways and Means, Representative Brian S. Dempsey, unexpectedly announced Thursday that he is resigning and joining one of the state’s top lobbying firms.

DeLeo and Dempsey were often seen as ideologically aligned on the more conservative end of the Massachusetts Democratic spectrum.

Sánchez earned his political chops working for the late Boston mayor Thomas M. Menino for about five years.

With his Senate counterpart, the House budget chief has a say on almost every major piece of legislation and takes the lead in making decisions about how the Legislature should appropriate billions in taxpayer dollars.

In good economic times, they must choose between a constant barrage of requests from fellow elected officials, lobbyists, and bigwigs. In a recession, the chairs must make hard decisions about what gets cut. It could be a decision, say, between less money for the Department of Children and Families, which serves the state’s most vulnerable youth, or fewer beds for the homeless.

And, of course, whether to raise taxes.

The state Constitution mandates that all “money bills’’ — essentially legislation that transfers property or money from people to the state — originate in the House. So if the House decides against raising taxes any year, representatives can thwart the Senate’s ability to hike them.

Asked if Massachusetts should raise taxes, Sánchez said hikes should be the final option and indicated a cautious approach, mentioning two successful ballot efforts to undo legislative tax hikes.

“I think we have a history of raising taxes in this House. We passed a gas tax, we passed an alcohol tax — the voters did repeal them,’’ he said.

After lawmakers raised the per-gallon gas tax by 3 cents to 24 cents and linked future automatic increases to inflation, voters in 2014 nixed the automatic increases.

And in 2010, voters repealed legislators’ effort to apply the sales tax to alcohol.

Sánchez called raising taxes “a last resort’’ but said he supported a tax on the highest earners that will be put to voters via a constitutional amendment on next year’s ballot.

First elected to the House in 2002, Sánchez represents a district that includes an economically and culturally diverse swath of two communities: parts of Jamaica Plain, Roslindale, and Mission Hill in Boston, and one precinct in Brookline.

Sánchez, married with two daughters, is a graduate of the University of Massachusetts Boston and Harvard’s Kennedy School of Government.

Born in New York to parents who were born in Puerto Rico, Sánchez grew up in Boston.

When he was 4 years old, his sister was sick, and their mother decided to move the family from New York to Boston in search of medical care.

“Columbia Presbyterian wanted to chop her up, and my mother wasn’t having it,’’ he recalled. But her sister lived in Boston. So the three of them moved into his aunt’s small apartment in Roxbury’s Mission Main projects, and his mom fought to get his sister better treatment.

Asked what it means to him that he will be the first Latino chairman of the House budget-writing committee, Sánchez took several seconds to gather his thoughts.

“I’m a son of the city,’’ he replied. “I’m proud because of who I am as a Puerto Rican man in Boston. And I know how important that is to a lot of folks. But at the end of the day, I’m a kid from Boston that’s just trying to do the right thing.’’

Joshua Miller can be reached at joshua.miller@globe.com. Follow him on Twitter @jm_bos and subscribe to his weekday e-mail update on politics at bostonglobe.com/ politicalhappyhour.