BOSTON — Voters head to the polls today to select a governor and decide congressional, statewide and legislative races in Massachusetts in a pivotal midterm election being billed as a referendum on Republican President Donald Trump.

Topping the ballot is a race for U.S. Senate that pits incumbent Democratic Sen. Elizabeth Warren against Republican Geoff Diehl in a contest framed largely around Warren’s criticism of Trump and her possible run for the White House in 2020.

The latest polls have shown Warren with a sizable lead over Diehl. Independent Shiva Ayyadurai is also on the ballot.

In the governor’s race, the Republican ticket features Gov. Charlie Baker and Lt. Gov. Karyn Polito seeking a second term.

They face Democrat Jay Gonzalez, a former state budget chief, and his running mate, Quentin Palfrey, a former Obama administration official. They have trailed Baker and Polito substantially in polls and fundraising.

Nearly 590,000 of the state’s nearly 4.5 million registered voters have already cast ballots, taking advantage of the early voting period, which ran from Oct. 22 to Nov 2. That’s roughly half the number of early votes cast ahead of the 2016 presidential election, the state’s first foray into early balloting.

Secretary of State Bill Galvin said he expects a turnout of about 2.4 million, slightly more than the 2010 and 2014 midterms.

Galvin, a Democrat who is seeking a seventh term, said national politics appear to be the driving force among early voters.

“That is truly driving the turnout, on both sides,” he told reporters at a briefing Monday. “It’s not necessarily the intensity of some of the statewide races because, candidly, some of them aren’t very intense. Or the absence of legislative contests, because there are many areas that have no legislative contests.”

Galvin said about 36 percent of the early ballots were cast by Democrats, about 10 percent were Republican and the remainder, 55 percent, were cast by unenrolled or independent voters.

Besides early voting, at least 125,000 voters have requested absentee ballots, he added.

Galvin’s challengers are Republican Anthony Amore and independent Juan Sanchez Jr. in a race that has revolved largely around allegations that the six-term secretary has used his office for political gain, a claim he denies.

Attorney General Maura Healey, a Democrat, faces a bid from Republican Jay McMahon, who has criticized her for filing numerous lawsuits against the Trump administration.

Democratic State Auditor Suzanne Bump faces Libertarian Dan Fishman, Republican Helen Brady and Edward Stamas, who is running on the Green-Rainbow ticket.

Six of the state’s 11 congressional seats are contested, including a three-way race to succeed outgoing U.S. Rep. Niki Tsongas, who is retiring after 15 years in Congress.

In that race, Republican Rick Green, a Pepperell businessman, faces Democrat Lori Trahan of Westford, and independent candidate Mike Mullen of Maynard.

U.S. Rep. Seth Moulton, a Democrat, seeks a third term in the 6th District amid challenges from Republican Joseph Schneider and independent Mary Jean Charbonneau.

Besides deciding state and federal races, Massachusetts voters will answer questions related to nurse staffing ratios at the state’s hospitals, whether to form a commission to study a constitutional amendment repealing the U.S. Supreme Court’s Citizens United ruling, and whether to uphold the state’s transgender protections in public restrooms and other places.

Nationally, the election will decide control of the U.S. House and Senate, with the outcomes expected to shape the next two years of Trump’s presidency.

Democrats need a net gain of 23 seats to build a House majority, while they need to flip a net of two seats in the Senate.

Polls in Massachusetts will be open today from 7 a.m. to 8 p.m.

Christian M. Wade covers the Massachusetts Statehouse for North of Boston Media Group’s newspapers and websites. 

2018 GENERAL ELECTION

U.S. Senate

Elizabeth A. Warren, Democrat*

Geoff Diehl, Republican

Shiva Ayyadurai, Independent

Governor/Lt. Governor

Charlie D. Baker/ Karyn Polito, Republican*

Jay Gonzalez/ Quentin Palfrey, Democrat

Attorney General

Maura Healey, Democrat*

Jay R. McMahon III, Republican

Secretary of State

Willam F. Galvin, Democrat *

Anthony Amore, Republican

Juan G. Sanchez, Green-Rainbow

Treasurer

Deborah B. Goldberg, Democrat *

Keiko M. Orrall, Republican

Jamie M. Guerin, Green-Rainbow

Auditor

Suzanne M. Bump, Democrat*

Helen Brady, Republican

Daniel Fishman, Libertarian

Edward J. Stamas, Green-Rainbow

Governor’s Council - 5th District

Eileen Duff, Democrat*

Richard A. Baker, Republican

Marc C. Mercier, Libertarian

Representative in Congress - 3rd District

Rick Green, Republican

Lori Loureiro Trahan, Democrat

Michael P. Mullen, Independent

Representative in Congress - 6rd District

Seth Moulton, Democrat*

Joseph F. Schneider, Republican

Mary Jean Charbonneau, Independent

State Senate - 1st Essex District

Diana DiZoglio, Democrat

Alexander Leighton Williams, Republican

State Representative - 1st Essex District

James M. Kelcourse, Republican*

Jennifer A. Rocco-Runnion, Democrat

State Representative - 2nd Essex District

Lenny Mirra, Republican*

Christina Eckert, Democrat

State Representative - 4th Essex District

Brad Hill, Republican*

Allison Gustavson, Democrat

Register of Deeds - Essex Southern District

John L. O’Brien, Jr., Democrat*

Jonathan E. Ring, Republican

David D. Colpitts, Unenrolled

Source: Secretary of State’s office (*Denotes incumbent)