Republican Mitt Romney says the November election against President Barack Obama will be a "close-fought battle."

Mitt Romney speaks as his sons Matt Romney (L) and Josh Romney look on during the regional Conservative Political Action Conference in Denver (Justin Sullivan/Getty Images)

He also says Obama is offering a vision for "trickle-down government" and that Americans saw "two very different visions for America" during the first presidential debate Wednesday night in Denver.

FULL COVERAGE: 2012 Presidential Campaign
FULL COVERAGE: Presidential Debates

The Republican nominee spoke Thursday morning during a surprise appearance at the Colorado Conservative Political Action Committee's meeting in Denver. A smiling Romney took the stage to sustained cheers from the audience of conservative activists.

Romney was introduced by four of his five sons. His appearance at the meeting came before a scheduled flight to Virginia, where he and running mate Paul Ryan were to address an evening rally.

(Copyright 2012 by The Associated Press. All Rights Reserved.)