An Israeli watches televisions broadcasting the speech of U.S. President Barack Obama in Cairo, at an electronics shop in Tel Aviv June 4, 2009. REUTERS/Gil Cohen Magen

President Obama's televised prime-time addresses are becoming a tougher sell to the broadcast networks than his sweeping health care reform has been to Middle America.

A day after news broke of the president's plan to address a joint session of Congress on health care issues in prime time Wednesday, not one of the Big Four networks has said it would carry the address live.

Among other things, the networks have been waiting to hear when the address will start, with sources indicating Thursday night that the White House was leaning toward 8 p.m.

After a brief post-inauguration honeymoon, the broadcast networks have become increasingly frustrated by the frequency of Obama's requests for prime-time coverage. The pre-emptions wreak havoc on the networks' schedules and cost millions of dollars in lost ad revenue.

Fox became the first network to break ranks in April by declining to carry the president's news conference after reportedly losing as much as $6 million by moving American Idol in February to accommodate Obama's second news conference.

In July, Fox again declined to cover an Obama news conference, with the other three broadcast networks showing reluctance to surrender prime-time real estate. It took several days and an agreement by the White House to move the event up an hour to 8 p.m. ET to get ABC and NBC in line.

To avoid a similar time-shifting snafu, the administration this time has been polling the networks about whether to schedule the live event at 8 or 9 p.m.

Regardless of the White House's final start-time decision, Fox is expected to sit out the Obama speech again, referring its viewers to sister cable channel Fox News.

The network has the most at stake because it premieres its new Wednesday lineup next week, including the season premiere of So You Think You Can Dance and the freshman season of the much-hyped comedy-drama Glee.

On Wednesday night, the network aired Dance and Glee specials promoting next week's premieres. On Thursday, it issued a couple of news releases touting the Wednesday debuts.

Also working in favor of a decision to stick to the regular schedule is the fact that Fox's Dance was a big ratings winner in July when it aired opposite Obama's news conference on ABC, CBS and NBC.

Much like last time, ABC and NBC would have to move their highest-rated summer series, Wipeout and America's Got Talent, respectively. If the speech to Congress airs at 8 p.m., the two shows again could be pitted against each other at 9 p.m.