Donald Lambro

WASHINGTON -- Hillary Clinton's mercurial campaign is reaping the law of diminishing returns. With each change in strategy, mood and tactics, she is falling further behind her arch nemesis, Barack Obama.

Nothing seems to be working for the New York senator who has tried four tone-of-voice changes and multiple personalities in an attempt to pierce Obama's cool, unflappable, self-confident demeanor.

Whether it's the experience strategy that proclaimed she was "ready to lead on day one," her attacks on his superior oratorical skills, the humbling admission she was proud to be in a race with Obama or the angry, over-the-top "shame on you, Barack Obama" for identifying her with the NAFTA pact she praised in her book -- nothing works. Her polling numbers keep drifting lower, and Obama's keep rising.

The disciplined Obama keeps his message focused on "change," while Clinton keeps changing her message.

It will all come unraveled next week on March 4 in Texas and Ohio, the two primaries that party leaders and strategists, including her husband, say she must not just win but must win decisively to stay in the race.

"Clearly, she needs to have a very good day on March 4 to regain her momentum," former Democratic National Chairman Steve Grossman told me.

"I think if we lose in Texas and Ohio, Mrs. Clinton will have to make her decisions as to whether she goes forward or not," Clinton adviser Harold Ickes told reporters this week.

With Obama holding a clear lead in the delegate race and assured of winning a big share of the 444 delegates at stake in next week's contests, which include tiny Rhode Island and Vermont, Clinton's candidacy looks hopeless.

Even Bill Clinton senses that after Obama's 11 straight primary/caucus victories, Texas and Ohio were slipping away from her. "If you don't deliver for her, then I don't think she can be (the nominee)," he said last week while campaigning in Texas.

In Texas, where 228 delegates were at stake, and where she once had a double-digit lead, polls now show the two rivals either in a dead heat or a slight lead for Obama.

In the battle for Ohio's 161 delegates, her huge 21 percent lead earlier this month has shrunk to seven points (50 percent to 43 percent) in recent polls. She will sweep Rhode Island, but Obama will take Vermont.

Collectively, polls show Obama with double-digit leads in Texas and Ohio among independents, the nation's fastest-growing voting bloc.

Donald Lambro

Donald Lambro is chief political correspondent for The Washington Times.