WASHINGTON — Sen. Hillary Rodham Clinton’s must-win states of Ohio and Texas are no cakewalk for her, largely because independents and crossover Republicans are welcome to vote in their Democratic primaries.

The political calendar of late winter has been less than kind to the embattled presidential contender, who once figured that a big day in early February would affirm her march to the presidential nomination and the rest would be icing.

Instead, it’s been slippery ice at every turn, and Ohio and Texas contests on March 4 matter greatly, crucial tests in her big-state fallback strategy.

The field in both states could be tilted to Sen. Barack Obama, despite Clinton’s presumed advantage among some voting groups and long-held if diminished leads in the states’ opinion polls.

Obama has displayed strengths dating to January among different voting groups that would normally be in tension with each other, and his drawing power has become more pronounced in his 11-contest winning streak heading into March 4.

The Illinois senator has mobilized his party’s left wing, a big help in caucus races where party activists and fired-up newbies are key. And he’s drawn crossover Republicans and independents to primaries in which they are allowed to vote.

Ohio and Texas make it easy for them to do so. If they do, it could boost Obama’s vote.

Among independents, Obama is leading Clinton by 14 percentage points in Ohio and by 13 in Texas, according to a Washington Post-ABC News telephone poll taken Feb. 16-20.

And the settling of the GOP race in John McCain’s favor is an enticement for Republicans to come out for the Democratic election that still matters.

Moreover, both states let people vote early. Obama, fresh from his Wisconsin victory on Tuesday, didn’t wait for the dust to settle before exhorting Texans to vote right away. “I don’t want you to wait until March 4,” he said. Clinton, with a head start in campaigning in Texas, also appealed for an early lock on votes.

In the 22 contested Democratic primaries so far, independents made up 22 percent of the vote and they supported Obama by an overwhelming margin of 64 percent to 33 percent. Crossover Republicans, a far smaller percentage in the Democratic primaries, backed him 55-33.

Yet Obama has had the left flank covered, too: a 52-44 advantage over the New York senator among those who consider themselves very liberal.

Pennsylvania on April 22 offers the biggest remaining delegate prize in a primary limited to Democrats — 158. Even there, Clinton and Obama are opening a pitched competition to bring many of the state’s nearly 1 million independents into the party in time to vote, an opportunity now accorded about 4 million Democrats.

That means money, swarms of volunteers and a March 24 deadline to wrap up paperwork from those they can get to join. It’s the kind of grunt work where Obama’s forces have excelled, but Clinton’s are giving no quarter.

No such barriers exist in Texas and Ohio, where any voter can show up. Texans can vote while shopping for their corn flakes, in grocery and chain stores doubling as polling stations since Wednesday.

Polls point to a deadlocked race in Texas, where health care tops the concerns of Democrats in one poll and where Hispanics could make up more than a quarter of voters — two Clinton pluses.

Obama’s counterweight: A confounding delegate allocation system that awards more delegates to urban areas with high concentrations of black and young voters. The Texas contest, a primary followed by limited same-night caucusing, will yield 193 delegates.

Clinton’s lead in Ohio polling has slipped into single digits, less than half of what it was only weeks ago. Union households, a considerable presence in the state, so far are behind her, and she is more trusted to deal with the economy in a state that is struggling on that front.

A secure firewall? Not so, judging by results to date.

In 22 primaries, voters who named the economy as their main concern marginally favored her, according to interviews with them. But the trend has been in Obama’s direction. Not only did he win strongly among such voters in Wisconsin, but he won overwhelmingly among them the previous week in Maryland and Virginia.

She has narrowly outperformed him in union households, another eroding advantage.

Ohio has 141 delegates at stake. Rhode Island and Vermont primaries March 4 offer 21 and 15 respectively.

Obama’s delegate total stands at 1,358.5, Clinton’s at 1,264, with 2,025 needed to claim the nomination. The awarding of half a delegate comes from expatriate and U.S. territorial Democratic contests.


Associated Press Writer Alan Fram contributed to this report.