Video (03:01) : Governor Mark Dayton will also undergo more testing after fainting Monday night while delivering his State of the State address.

Gov. Mark Dayton revealed Tuesday that he has been diagnosed with prostate cancer, a new personal challenge for a governor who has struggled with health problems throughout his term and is just embarking on his last two years in office

Dayton disclosed his diagnosis at a news conference the morning after he collapsed during his State of the State speech, cutting the address short and rattling several hundred state legislators and others gathered in the House chamber. Back in front of the cameras Tuesday morning, Dayton said his early prognosis is good, and that he expects to learn more after a follow-up consultation at Mayo Clinic next week to discuss treatment options.

“I don’t expect it to, within a very short period of time, impede my performance of my responsibilities,” Dayton said. “We’ll know more next week.”

The DFL governor, who turns 70 on Thursday, said that his recent annual physical examination detected a tumor in his prostate. A biopsy last week confirmed the cancer diagnosis, he said. He did not reveal the stage of the cancer, saying only it had not spread to other organs.

A Mayo Clinic spokesman said that Dayton’s physician does not believe the fainting episode is related to his cancer, attributing it instead to back pain and possible dehydration.

Dayton said he expects to serve out the remainder of his term, which ends in early 2019. He talked about his health Tuesday morning at a previously scheduled event to release his $46 billion, two-year state spending proposal. But the diagnosis is likely to complicate the push for Dayton’s ambitious agenda in the legislative session that got underway at the beginning of January, and add more burden to his intensely demanding, high-profile job.

Gov. Mark Dayton left the news conference after announcing that he had prostate cancer Tuesday, a day after fainting while delivering his State of the State address.

Recent health problems besetting Dayton include two surgeries in recent years to relieve back and leg pain, leading to questions about whether the governor is up for the daily rigors of leading the state.

“I think I am,” Dayton said. “If I don’t, I won’t continue, but I believe I am. I’ve said when I had my hip surgery there are no brain cells in my hip. As far as I know, there are no brain cells in my prostate either.”

Dayton struck a jocular tone while sharing his news, cracking wise about the diagnosis and the fainting episode. He also read the last few minutes of his unfinished State of the State speech. But he said he considered himself lucky after hearing about friends who have received the same news.

“I always thought I was incredibly fortunate because cancer seemed to be like Russian roulette,” Dayton said, describing it as grim but not uncommon for men his age.

“Every time I get a clean bill of health at my annual physical I’m on my knees thanking the Lord for that clean bill of health. ... I feel very blessed at having had a healthy life as I’ve had despite some of my recent surgeries,” Dayton added.

Dayton underwent additional testing later Tuesday at Mayo Clinic in response to his collapse. About 40 minutes into his speech, Dayton paused for a long drink of water, but then appeared unable to begin speaking again. He then slumped forward and struck his head on the lectern. Several people nearby, including Lt. Gov. Tina Smith and Secretary of State Steve Simon, helped move Dayton onto a nearby bench; two doctors and several emergency medical technicians who are members of the Legislature rushed forward to provide aid. He was reportedly conscious again almost immediately.

A clinic spokesman said Dayton’s physician determined the fainting spell was “situational and related to standing for a long time while giving his speech and possible dehydration. It is not related to his prostate cancer diagnosis.”

Dayton previously fainted at a political fundraiser in Woodbury a year ago, and spent the night at Regions Hospital. Dayton’s staff also attributed that to possible dehydration and back and leg pain caused by standing in one place for too long. Dayton’s back and leg problems have left him often unsteady on his feet in recent years, and he has taken to frequently walking with a cane.

The governor’s most recent back surgery was in December 2015 at Mayo Clinic, where he also had a similar surgery in 2012. The neurosurgeon who operated on him in 2015 said at the time the governor was suffering from spinal stenosis, a common condition akin to arthritis, in which bone spurs that grow on the spine pinch nerves in the area.

The condition frequently leads to weakness and instability in the legs and is often treated with surgery.

The Mayo spokesman did not offer any more details about Dayton’s cancer diagnosis.

Legislators supportive

The news of Dayton’s cancer diagnosis stunned lawmakers and other state political leaders who had just witnessed him collapse the night before. Legislative leaders on Tuesday offered statements of support, even as they criticized the budget Dayton had just unveiled.

“We don’t have to agree on everything politically to care about each other as humans. We certainly want the best for him,” said House Speaker Kurt Daudt, R-Crown.

“At our core, we’re all Minnesotans and we recognize he’s going through something serious and we’re going to be careful about how we do things,” added Senate Majority Leader Paul Gazelka, R-Nisswa.

The governor’s staff and Cabinet commissioners have had experience with the governor’s absences during his recoveries from past health setbacks. Early in 2014, the year Dayton ran for re-election, he spent several weeks in a body cast that relegated him to his St. Paul residence. It became de facto headquarters for the governor, his commissioners and his staff as they carried on with official duties.

After laying out his budget proposal, Gov. Mark Dayton announced Tuesday that he had prostate cancer.

Dayton said he had not planned to publicly reveal his cancer diagnosis until after next week, when he expects to learn about treatment options at a follow-up consultation. But he decided after Monday night that he could no longer keep it secret.

“People deserve a governor who is on the job, qualified to perform the job intellectually and physically, and I believe I am,” Dayton said.

In late 2015, the governor’s father, former retail executive Bruce Dayton, died at age 97. Dayton revealed that his father had been diagnosed 25 years earlier with prostate cancer, but made a full recovery and never relapsed.

Staff writers Erin Golden and Jeremy Olson contributed to this report.