Updated

A conservative media watchdog organization charged Wednesday that the network morning news shows have spent considerably more time this year on Democrats running for president than on Republicans.

Network news executives rejected any suggestion of bias, and said they have a considerably harder time getting Republican candidates to appear on their shows.

Through July 31, the ABC, CBS and NBC morning news shows devoted 284 campaign segments to Democratic candidates and 152 to Republicans, according to the Media Research Center. Another 81 stories discussed both parties or a possible independent run by New York City Mayor Michael Bloomberg.

Get the latest campaign news in FOXNews.com's You Decide 2008 Center, learn about the candidates in the Eye on the Issues Center and read the daily Update '08 newsletter.

"The double standard has got to stop," said L. Brent Bozell, the group's founder. "What you hope is that there would be fairness. If you are going to give that much coverage to the Democrats, give it to the Republicans, too."

The disparity was most pronounced in January, with 52 stories on the Democratic campaign and five for the Republicans. That's the month that the campaign rivalry between Democrats Hillary Clinton and Barack Obama began.

PHOTO ESSAYS: 2008 Democratic Presidential Candidates and 2008 Republican Presidential Candidates

News executives say they strive for fairness, but the Clinton-Obama January jockeying is an example of how news drives their airtime decisions.

"You've got a former first lady and a black senator fighting for the nomination," said Jim Bell, executive producer of NBC's "Today" show. "That's historic. We're not going to make apologies for covering that."

Stories about the cancer relapse of Democrat John Edwards' wife Elizabeth were also counted in the total. It's unfair to count a personal story like that in a tally that suggests bias, said Jim Murphy, executive producer of ABC's "Good Morning America."

The news executives also said Democratic candidates have been far more willing to appear on their programs than Republicans.

Republican Rudolph Giuliani and potential GOP rival Fred Thompson both have standing invitations to appear on "Today," Bell said. Giuliani has been on once and Thompson has repeatedly refused the network he recently worked for (on the prime-time show "Law & Order"), he said.

"Good Morning America" announced this spring that the three top candidates from each party were invited for hourlong town meetings. Clinton and Edwards have both already appeared, and ABC is trying to work out a date with Obama, Murphy said.

None of the Republicans have committed to a town hall meeting, he said.

"The candidates are responsible for how much time they generally get," Murphy said. "They can get it by agreeing to interviews and agreeing to forums."

Bozell conceded that Republicans have shown a more pronounced reluctance to go on the air. He said the Democratic candidates have also been more forceful in pushing their campaign agendas in the early stages.

His group complained that too many of the stories on Republicans emphasized the candidates' flaws. But the morning show executives noted that one of the biggest stories of the GOP campaign has been the flagging candidacy of John McCain.

Bozell said the performances of "Today," "Good Morning America" and "The Early Show" on CBS should be watched closely because of their importance in reaching more than 10 million viewers each day.

Get full election coverage in FOXNews.com's You Decide 2008 Center, learn about the candidates in the Eye on the Issues Center and get the daily Update '08 newsletter.