Liz Cheney, the older daughter of former Vice President Dick Cheney, announced Tuesday that she intended to challenge Senator Michael Enzi in a Republican primary clash next year that national and state party officials had hoped to avoid.
"I am running because I believe it is necessary for a new generation of leaders to step up to the plate," Ms. Cheney, 46, said in a video posted on the Web.
Ms. Cheney made no mention of Mr. Enzi, 69, and focused most of her criticisms on President Obama, who is deeply unpopular in Wyoming.
But along with the generational swipe at Mr. Enzi, she implicitly took a shot at his low-key and consensus-oriented style, saying that "we can no longer afford simply to get along to go along" and declaring that Wyoming needed "a strong voice in Washington."
Word of Ms. Cheney's announcement went out just minutes after Mr. Enzi, in a barely veiled message to Ms. Cheney, issued his own statement that he would seek a fourth term.
Mr. Enzi said he was not notified before the video went out by either Ms. Cheney or her father — whom he has known for over 30 years — about Ms. Cheney's intentions.
"I thought we friends," he added.
Her ambitions had been rumored since she moved from suburban Washington to the Jackson Hole, Wyo., area last fall and immediately became a regular at state political and civic events. Ms. Cheney, a former senior State Department official in President George W. Bush's administration, is now a Fox News contributor.
She will have to overcome some local suspicions in Wyoming.
In the video announcing her candidacy, Ms. Cheney seemed to acknowledge as much. Pre-empting charges of carpetbagging, she noted that her family first came to the state in 1852. Her ancestors, she said, included ranch hands and one county's first female deputy sheriff.
