Rhode Island, demographically similar to Ohio, also proved lucky for Clinton, who defeated Obama by 58 percent to 40 percent there.
Texas saw a neck-and-neck Democratic presidential race, with Latinos and African American voters playing a key role.
CNN exit polls showed that Clinton won 67 percent of the Latino vote while Obama garnered 83 percent of the black vote in the state. Latinos make up 34 percent and blacks 19 percent of total Democratic voters in Texas.
The populous states of Ohio and Texas will offer a proportional combination of 334 delegates to Democratic candidates, which could be the big deciding factor in the choice of the party's presidential nominee.
Despite a big win Tuesday, Clinton still failed to overtake Obama in the number of delegates. Obama's share has increased sharply as a result of 11 straight victories over the past month.
"We know this: no matter what happens tonight, we have nearly the same delegate lead as we had this morning, and we are on our way to winning this nomination," Obama told supporters in Texas after winning the Vermont primary at 60 percent, compared with Clinton's 38 percent.
Political analysts had predicted earlier that victories in Ohio and Texas could stop Clinton's campaign from slipping toward the end, but she was unlikely to restore her lead without winning by a big margin.
A Democratic candidate needs to garner 2,025 delegates of the total 4,049 to secure the party's presidential candidacy.
(Xinhua News Agency March 5, 2008)
