Gannett Co. on Monday offered to buy Tribune Publishing Co. for about $815 million, including the assumption of $390 million in Tribune debt.

Tribune, based in Chicago, owns the Los Angeles Times and San Diego Union-Tribune, as well as the Chicago Tribune. Gannett, based in McLean, Va., owns more than 100 papers including USA Today and Ventura County Star.

“The Gannett board unanimously believes that the acquisition of Tribune would deliver substantial strategic and financial benefits for the combined company,” Gannett Chairman John Jeffry Louis said in a statement. “A combination with Tribune would rapidly advance Gannett’s strategy to grow the USA Today Network, the largest local-to-national network of journalists in the country, to include more local markets and new platforms.”

Gannett’s all-cash offer would give Tribune stockholders a 63 percent premium to the closing price of Tribune stock on April 22.

Along with its announcement, Gannett released a letter it sent to Justin Dearborn, chief executive at Tribune, in which Gannett expressed disappointment that Tribune had rebuffed its offer and confidence that Tribune’s non-management stockholders will support the proposal.