CHICAGO - The financially struggling Chicago Tribune will undergo yet another metamorphosis, announcing Tuesday that it will launch a smaller, tabloid-size version in an apparent bid to deliver a blow to the rival Chicago Sun-Times.

The tabloid, which will have the same content as the 162-year-old Tribune's traditional broadsheet, will be available at stores, newsstands, train stations and newspaper boxes starting on Monday, a Tribune statement said.

Many commuters have tended to favor the tabloid-size Sun-Times during rush-hour, seeing it as a less cumbersome format than longer, multi-section broadsheets - an advantage one Tribune executive alluded to Tuesday.

"Many news consumers have asked for a more convenient version of the paper that contains all of the same great news and information," Tony Hunter, CEO of Chicago Tribune Media Group, said in the statement.

Home-delivery subscribers still will receive Tribune's broadsheet. The RedEye, Tribune's free commuter tabloid that has far less content than the main paper, will remain unchanged.

The newspaper's latest initiative comes a month after its parent company, Chicago-based Tribune Co., filed for Chapter 11 bankruptcy protection amid a multi-billion-dollar debt and falling ad revenue.

The Sun-Times' parent, Sun-Times Media Group Inc., also has buckled under enormous financial strain.

The tribulations of the two Chicago dailies have raised questions about whether at least one could go under, leaving this city of 3 million people with just one mainstream daily.

The Sun-Times expressed confidence that it could compete with the Tribune's tabloid.

"They've tried to knock us out for a long time, but they haven't yet," said Sun-Times spokeswoman Tammy Chase, adding that the paper was flattered by Tribune's decision to adopt a format so closely associated with its rival.

"But we've been doing the tabloid thing a long time and we're good at it," she said.

The Tribune has scrambled to hold on to readers increasingly drawn to the Internet for news.

Several months ago it dramatically redesigned its broadsheet, collapsing content by eliminating some individual sections, increasing white space and making photographs more prominent. But after readers objected to some of the changes, the Tribune said it would tweak the design.

By launching a tabloid, the Tribune might hope to cut into its rival's market share, particularly in single-copy sales, said Mary Nesbitt, associate dean at Northwestern University's Medill School of Journalism.

"They are being more aggressive and there's been a pattern of that over the past several years," she said.

A single newspaper putting out two versions with the same content is uncommon, including because it entails higher costs, said Nesbitt. But, she added, "it's not necessary too costly if it weakens your competitor in the long run."

Tribune spokesman Michael Dizon declined to say that the new tabloid was aimed primarily at undercutting the Sun-Times.

"We are very competitive, and we compete not only with the Sun-Times but with other media," he said.