No sooner had Senator Blanche Lincoln promised to deliver one crucial vote in support of a health care overhaul than she threatened to withhold the next one.
Her clear warning that she would oppose the Democratic plan in its current form is certain to keep her squarely at the center of the increasingly contentious health care fight and intensify a campaign in Washington and back home to put her on the spot in advance of a re-election bid next November.
Mrs. Lincoln, Democrat of Arkansas, said that more than $3 million in health care advocacy advertisements aimed at her had already been broadcast in Arkansas. But she insisted Saturday that her position on health care would not be shaped by political considerations.
“I’m thinking about the 450,000 Arkansans who have no health insurance,” she said as she lent her support to an initial procedural step in the most closely watched floor speech of the day. “I’m not thinking about my re-election, the legacy of a president or whether Democrats or Republicans are going to be able to claim victory in winning this debate.”
Yet the political implications are inescapable. Of the swing-state Democrats struggling with the health care issue, Mrs. Lincoln, a 49-year-old mother of twins who is married to a physician, is one of the few set to be on the ballot next year. Republicans are lining up to oppose her in a state where President Obama performed badly in the 2008 election.
Mrs. Lincoln was the Democrat whose vote on opening the debate was most in doubt, though most expected that she would ultimately side with her Democratic colleagues.
Senator Mary Landrieu of Louisiana, who revealed her position shortly before Mrs. Lincoln did, was considered safely in the Democratic fold, particularly after $100 million in added Medicaid money for her state was included in the measure. Republicans have nicknamed that provision the Louisiana Purchase.
As the final Democrat to reveal her position, Mrs. Lincoln helped Republicans define her as the decisive 60th vote to move the health care debate forward. The National Republican Senatorial Committee immediately issued a press release trying to make her responsible for the bill.
“The debate wouldn’t have happened without her vote and I think that will be an issue,” said Senator John Cornyn of Texas, chairman of the Senate Republican campaign group.
The health care fight has come at a time when Mrs. Lincoln’s influence is increasing in the Senate. A committee shuffle after the death of Senator Edward M. Kennedy elevated her to chairwoman of the Agriculture Committee, a position that could allow her to protect her agriculture-heavy state.
But the health care fight has been divisive at home; House Democrats from the state split on their version of the bill earlier this month. Senator Mark Pryor, a fellow Democrat from Arkansas, was re-elected last year and has managed to escape much of the frenzy.
Some Democrats and other observers say they believe Mrs. Lincoln can make a case that her central role in the debate is a positive development in a state where people lack health insurance at a higher rate than the national average. The Democrats’ bill would offer subsidies to low- and moderate-income people to help them buy insurance.
Ray Hanley, who was the Medicaid director in Arkansas from 1986 to 2003, said that “in a poor state like Arkansas, where nearly 500,000 people are uninsured, many would benefit from the subsidies.”
But Mrs. Lincoln has to juggle their interests with those of business leaders and others in Arkansas opposed to the measure. She said it was her constituents’ views and needs — not the contents of political commercials — that would determine her position.
“My first loyalties are with the people of Arkansas,” she said. “Not insurance companies, the health care industry or my political party.”
Robert Pear contributed reporting.
This article, first appeared in The New York Times.