That same day, Demma sent a message from his Blackberry to several well-connected Republicans, boasting of an imminent run for the office.
"Our LG will, unless he becomes GOV in the interim, file to run as a GOP representative for the US Senate seat in 2010, regardless of who might also be in that race - the incumbent, included," read the message sent from Demma's Blackberry.
Bennett, now in his third term, has begun fundraising and assembling a campaign staff for a re-election bid in 2010. He would be 83 years old at the end of that term.
Demma denied sending the Blackberry message - which had a code distinctive to his device - saying it would be "stupid" to send it, but admitted he added the Facebook post - which has since been removed - and said Herbert was considering all of his options.
"Everything is in play," he said. "Currently we're getting re-elected as lieutenant governor and we'll see how things play out."
But on Monday evening, Herbert was categorical in denying designs on the Senate seat.
"I just want to make sure we squelch any talk or rumor. I have absolutely zero, less than zero, interest of running for Senate, certainly against my good friend Robert Bennett," he said.
Herbert said he hasn't seen his chief of staff's claims, but he said they would discuss the issue.
"I support Senator Bennett. I think he's doing a great job back there. He's been a longtime friend of mine and there's nothing he's done or hasn't done that would make me want to run against him."
Earlier in the day, Demma had said that Herbert was at a family function for two days and couldn't be reached. But Herbert called The Tribune after receiving a call from Huntsman's chief of staff, Neil Ashdown.
Bennett had left a message with Herbert and also spoke with someone in the governor's office, Herbert said.
"Governor Huntsman is running for governor and he doesn't know of any other plans that his running mate has," said Huntsman's spokeswoman, Lisa Roskelley.
Herbert was re-nominated Saturday along with Gov. Jon Huntsman Jr. for a second term. Both Herbert and Bennett were running as delegates to the Republican National Convention and Herbert finished well ahead of Bennett among voting delegates. But Herbert says he is only interested in helping Huntsman get re-elected.
"I'm the lieutenant governor. I'm enjoying working with Jon Huntsman. That's what I'm going to be. That's my area of expertise and where I think I can do some good in the state."
* THOMAS BURR contributed to this report.