In a blow to political junkies but a possible boon to the city's overtime budgets, Democratic presidential candidate Barack Obama's Thursday rally in Madison has been canceled, campaign officials said.

Senior adviser Robert Gibbs said in a statement that Obama was changing his schedule on Thursday and Friday to visit his ailing grandmother, Madelyn Dunham, who helped to raise Obama in Hawaii.

"In the last few weeks, (Dunham's) health has deteriorated to the point where her situation is very serious," Gibbs said.

Wisconsin campaign spokesman Matt Lehrich said he couldn't rule out a later Obama visit to the state before the Nov. 4 election but that there was nothing concrete as of late Monday.

The news comes as polls continue to show a double-digit lead in Wisconsin for the Illinois senator over Republican rival John McCain but tighter races in other states like Ohio, Florida and Indiana — that last state a spot where Obama is expected to campaign on Thursday morning before taking his time off.

On Friday, the Obama campaign had said that the candidate was planning the Downtown rally on the Capitol Square not far from the site where then Democratic contender John Kerry and rocker Bruce Springsteen drew an estimated 80,000 people in 2004.

The latest Mason-Dixon/NBC poll of 625 likely voters in Wisconsin shows Obama with 51 percent of the vote to McCain's 39 percent in the state. The poll's margin of error was plus or minus 4 percentage points.

Mark Jefferson, executive director of the state Republican Party, said Wisconsin was still in play. He said Republicans are contacting larger numbers of voters this year by doing phone calls and house visits.

"We're going to close strong and John McCain has come back from behind before and we're really still within striking distance," Jefferson said.

UW-Madison political scientist Charles Franklin said other states, including more populous ones such as Ohio and Florida, appeared to be much tighter in current polls than Wisconsin. In an interview Monday before the Obama campaign had released Obama's personal reasons for the decision, Franklin said it made strategic sense for Obama to focus on those states.

"For (Obama) to spend the last 14 days more in those states and less in ones that look pretty good for him right now is certainly a sensible campaign decision," Franklin said.

There is one upside to the cancellation for Obama supporters and curious residents who had been hoping to see the candidate up close.

Kerry's visit in 2004 cost the city of Madison $60,000 for barricades and signs for streets that had been shut down and for overtime for police and fire department staff, said Rachel Strauch-Nelson, a spokeswoman for mayor Dave Cieslewicz. That amount was billed to the Kerry campaign but never paid, Strauch-Nelson said.

Strauch-Nelson couldn't say whether the subject of that unpaid bill had come up last week, when both Kerry and Cieslewicz spoke at a Madison rally to urge voters to cast early absentee ballots for Obama.

Strauch-Nelson said that, had the rally occurred, the city would have also tried to work with the Obama campaign to be reimbursed for any costs.

State Journal reporter Dean Mosiman contributed to this article.