BERLIN — Voters in two southwestern German states are kicking off an election year on Sunday that could change the course of Europe’s largest economy after 16 years under the leadership of Chancellor Angela Merkel, who will be stepping down after a new government is sworn in.

The elections in the states of Baden-Württemberg and Rhineland-Palatinate are the first in a year that will see voting for new legislators in four more states, and for the country’s Parliament, which will be elected in September.

Sunday’s voting is taking place after largely muted election campaigns that were overshadowed by the threat of the coronavirus and by lockdowns. While neither race will serve as a clear bellwether for the fall election, the outcomes could indicate how voters are feeling about the two leading parties, the conservatives and the Greens, and help focus the contest for Ms. Merkel’s replacement.

“It is an unbelievably exciting election year,” said Thorsten Faas, a professor of political science at Berlin’s Free University. “A lot is still open, creating the possibility for movement in various directions.”

A vaccine rollout stymied by shortages of doses and hampered by bureaucracy is leading many to question the competence of the chancellor’s conservative bloc. Over the past week, revelations have emerged that several conservative lawmakers earned tens of thousands of euros in exchange for arranging the sale of medical-grade masks to municipalities early in the pandemic, when supplies were very tight.

Three lawmakers have resigned over the scandal, including a member of the Christian Democratic Union representing a district in Baden-Württemberg. Another lawmaker from the state of Thuringia, as well as a member of the Christian Social Union, the conservative party in the state of Bavaria, also resigned. After the payouts came to light, party leaders required all 240 conservative lawmakers to sign a declaration pledging they hadn’t used their position for financial gain in connection with fighting the pandemic.

Even before the scandal broke, the conservatives were struggling in the race in Baden-Württemberg, where a popular incumbent governor for the Greens is seeking a third term in office.

For the past five years, Winfried Kretschmann, 72, has led the state through a coalition of his environmental party with the conservative Christian Democrats, and voters are expected to return him to office. Polls in the weeks running up to the vote showed the Greens with the strongest support, between 33 to 35 percent. Mr. Kretschmann campaigned on his personality, under the slogan “You know me,” and promised a continuation of his party’s consensus-seeking policies of the past five years.

Polls suggest the Christian Democrats in Baden-Württemberg appear poised to take second place, setting the stage for a possible continuation of the current coalition, a combination that many observers consider a possibility for the makeup of the national Parliament.

The Alternative for Germany, or AfD, is expected to hold onto the roughly 15 percent support that it won in Baden-Württemberg in 2016. Although the regional party has been plagued by internal divisions and strife among its members, it is expected to retain voters who are attracted to its nationalistic, anti-establishment stance.

Given the pandemic, many of the state’s 7.7 million voters cast their ballots by mail weeks before the election, raising questions about how much of an impact the recently exposed mask scandal could have on the outcome. Still, the final days of the election saw the tide shift toward the Greens, said Arne Jungjohann, a political scientist with the Heinrich-Böll Foundation, that is associated with the Green party.

“Conservatives are preparing for the worst,” Mr. Jungjohann said.

In neighboring Rhineland-Palatinate, where 3.1 million people are eligible to cast ballots, the conservatives had been running a stronger race in their attempt to bring an end to 30 years of governments led by the Social Democrats, despite also facing a popular incumbent governor, Malu Dreyer. The Social Democrats in the state have been leading in the polls, with around 33 percent support, compared with 29 percent for the conservatives, although their candidate is less familiar to voters.

If the conservatives do badly on Sunday’s elections, it could reflect badly on Armin Laschet, who took who took over as leader of the Christian Democratic Union in January.

Normally the party would put forward its leader as the candidate in the race for the chancellor, but Mr. Laschet has so far proved to be less popular with the German public than the governor of Bavaria, Markus Söder, who could instead be tapped as the conservative candidate.

Mr. Söder, who is also the head of the Bavaria-only Christian Social Union, has raised his profile as someone who takes tough, decisive action to halt the spread of the pandemic in his state, closing the border to Austria and sending vaccines to help the beleaguered Czech Republic.

Mr. Laschet has said the conservatives will decide in the coming months whether the head of the Christian Democratic Union or the head of the Christian Social Union will run in September as the conservative bloc’s candidate for chancellor. But if the Christian Democrats take a beating in Sunday’s elections, they might decide faster.

Whoever is selected will face the Greens’ candidate, who has yet to be named, and Germany’s finance minister, Olaf Scholz, who is running for the Social Democrats.

Support for the Greens has nearly doubled since the election in 2017, making them the second strongest party heading into the national election, after the conservatives and ahead of the Social Democrats.