Presidential candidates Hillary Clinton and Barack Obama waged a tight campaign fight across Ohio on Sunday as a top Democrat voiced concern about a prolonged party battle after Tuesday's voting.
Four states hold contests on Tuesday to select Democratic and Republican candidates for the November election, with Clinton and Obama focusing most of their effort on the two big states of Texas and Ohio.
Both races are very tight after Clinton held big leads a month ago, according to a Reuters /C-SPAN/Houston Chronicle poll released on Sunday.
Obama led in Texas 47 percent to 43 percent while Clinton led by a statistically insignificant one point in Ohio, 47 percent to 46 percent, the poll showed. The poll had a margin of error of 3.7 percentage points.
Obama, a senator from Illinois who would be the country's first black president, leads in the race for the 2,025 delegates needed to win the nomination at the party's summer convention. Unless Clinton wins by very big margins on Tuesday, he will pick up big chunks of additional delegates, and her future would be uncertain.
The Republican front-runner, Arizona Sen. John McCain, faces dwindling competition from the only other major Republican candidate, former Arkansas Gov. Mike Huckabee, and took the day off from the campaign trail.
A big night on Tuesday could put McCain very close to the 1,191 delegates he needs to clinch the Republican nomination.
Polls close in Ohio at 7:30 p.m. EST and all voting in Texas will be over at 9 p.m. EST.
While Clinton, a New York senator who would be the first woman president, and Obama battled it out, one of their former Democratic rivals, New Mexico Gov. Bill Richardson, was worried that the fight might continue past Tuesday.
"The concern that I have is the bickering that took place between those two very fine senators is going on too long," Richardson, who bowed out of the Democratic race early last month, said on CBS's "Face the Nation" program.
Richardson has been the object of attention from both camps since he dropped out because, as one of the top Hispanic office holders in the United States, he could have impact with Hispanic voters, especially in Texas on Tuesday.
Many Democrats fear a prolonged battle would divide the party and give a boost to McCain, who will have time to establish his candidacy.
"We have to have a positive campaign after Tuesday," Richardson said. "Whoever has the most delegates after Tuesday, a clear lead, should be, in my judgment, the nominee."
But Tuesday was two days off and the candidates were going full speed across Ohio stressing their campaign themes - Clinton stressing her experience against what she describes as her opponent's vacant rhetoric, while Obama touted his judgment and new outlook versus her commitment to status-quo politics.
Westerville, Ohio, a suburb of the state capital of Columbus that once was home to the Anti-Saloon League, became an unlikely political ground zero on Sunday with Clinton appearing in the morning and Obama later in the day.
Mocking Obama as just a speech-maker and not a person of action, Clinton told a rally, "I've given a lot of speeches in my life, probably, I don't know, hundreds of thousands. Sometimes I finish a speech and people come up to me and say, 'Oh that was so inspiring and wonderful and it made me feel so good.'"
"I say, well that's great. But that's just words. Our job is to make a difference," she said.