Today's presidential primary contests
Ohio primaries
Voting: 6:30 a.m.-7:30 p.m. EST.
At stake: Democrats, 141 delegates; Republicans, 85 delegates.
Democrats: Hillary Clinton has a narrow lead in the polls and the endorsements of popular Governor Ted Strickland and former US senator John Glenn. Barack Obama is counting on an extensive grass-roots operation. The economy and trade are the big issues.
Republicans: John McCain could mathematically clinch the nomination with a strong showing, and he holds a comfortable lead in the polls over Mike Huckabee.
Rhode Island primaries
Voting: Polling places open between 7 and 9 a.m., all polls close at 9 p.m. EST.
At stake: Democrats, 21 delegates; Republicans, 17 delegates.
Democrats: The nation's smallest state has long been friendly to the Clintons, and Clinton has the support of its Democratic establishment. But Obama is closing fast in the polls.
Republicans: McCain has an overwhelming lead in the polls.
Texas primaries
Voting: 8 a.m.-8 p.m. EST (polls in three counties close at 9 p.m. EST).
At stake: Democrats, 193 delegates; Republicans, 137 delegates.
Democrats: Obama has a slight lead in some polls, though others show a tossup. Even if Clinton wins the popular vote, Obama could emerge with more delegates because of the way the state divvies them up and its unique hybrid election setup.
Republicans: Huckabee has been focusing his efforts in the Lone Star State, but still trails McCain by well into the double digits in polls.
Vermont primaries
Voting: Polling places open between 7 a.m. and 10 a.m., all polls close at 7 p.m. EST.
At stake: Democrats, 15 delegates; Republicans, 17 delegates.
Democrats: Obama holds a commanding lead in the polls and is expected to win easily, as he did in neighboring Maine.
Republicans: McCain has a huge lead in the polls.
GLOBE STAFF 