"This is so important for [Republicans]," Tancredo said. "I don't think Scott can win a general election. That's the bottom line here."
"I am going to do what I can do to either make sure it's me or a candidate that will do what it takes to turn this state around," Tancredo said.
Tancredo also said that Denver Mayor John Hickenlooper, the only Democrat in the race, will likely win in November and be the next governor.
"It's going to be tough for any Republican. It's going to be tough for Scott," Tancredo said.
Earlier, Tancredo told 9NEWS that McInnis was ending his candidacy. McInnis' campaign refutes that claim.
On Thursday morning, Tancredo told 9NEWS the latest development Wednesday night "probably sinks the ship" for McInnis. The gubernatorial candidate held a conference call Thursday morning with the senior members of his campaign staff.
Sean Duffy, a spokesman for McInnis' campaign, dismissed Tancredo statements Thursday.
"We're not going to respond to any of that. You're going to get a lot of e-mails and speculation today, but Scott's in the race," Duffy said. "He has the same schedule we planned for him last week. There's no change. We're moving forward. He's not going to talk much more about this. At some point you've got to draw a line, and we've answered everyone's questions already."
A former presidential candidate, Tancredo also personally called for McInnis to resign his candidacy. He is the first Colorado Republican to call for McInnis to resign from the race.
On his Facebook page, McInnis updated his status on Thursday to read: "I am in it to win it. We will continue to fight for Colorado's businesses and families and will not leave this race. Stay strong!"
McInnis' campaign came under fire this week when The Denver Post reported whole sections of his "Musings on Water" piece were copied from a 1984 article written by now-Colorado Supreme Court Justice Gregory Hobbs.
McInnis, who was paid $300,000 by the Hasan Family Foundation to pen his "Musings," tried to downplay the plagiarism allegations as a "non-issue" and a political tactic; and blamed a research assistant named Rolly Fischer for the plagiarized passages.
Fischer has not returned calls from 9NEWS. According to a television report, Fischer refused to sign a letter admitting blame prepared by the McInnis' campaign.
"Last night, the researcher in question basically called the former Congressman - a family friend of his for decades - he called him a liar," 9NEWS Political Reporter Adam Schrager told 9NEWS 8 a.m. "And the headline in the newspaper today might be the worst headline the McInnis campaign has seen since all of this started breaking, which is: 'Engineer: McInnis is lying.'"
McInnis admitted to 9NEWS "mistakes were made" and said he was sure the water writings were rife with examples of plagiarism.
Attorney General John Suthers spoke about the situation on Thursday. He says as the state's chief legal officer and lawyer for the Secretary of State, he recognizes that there could be legal issues that arise out of this. However, he says it would be inappropriate to comment to any great extent.
"I'll simply say as an elected office holder in Colorado that this is a serious matter, these allegations are serious. Mr. McInnis is going to have to make some tough decisions. If he stays in the race, voters are going to have to make some tough decisions in primaries or general election, but those are decisions that other people have to make," Suthers said. "My role as Attorney General, I'll deal with whatever legal issues arise out of it, any questions that were posed by the Secretary of State, we'll answer the very best we can given our legal expertise."
Colorado Republican Chairman Dick Wadhams released a statement on Thursday, but did not directly comment on the McInnis issue.
"I am proud of the open and fair nomination process that began this past March when more than 25,000 Colorado Republicans participated in precinct caucuses leading up to our recent state assembly. The caucus-assembly and petition processes have determined what candidates will appear on the primary election ballot and that is how it should be," Wadhams said. "Hundreds of thousands of Colorado Republicans will vote in the primary election to determine our nominees for every office from county commissioner to U.S. senator and governor and that is how it should be."
On Wednesday, 9NEWS spoke with Dr. Malik Hasan, who sits on the foundation board and who hired McInnis to write the articles.
"I thought he [McInnis] was a straight arrow. Now I am not sure I know him anymore," Hasan said. "If it is plagiarism, then the foundation will ask for a return of the money."
Hasan went on to say, "A year ago, if you would have said he would be accused of plagiarism, I would have said you were crazy."
Also on Wednesday, a second allegation of plagiarism surfaced, but the McInnis campaign says that allegation is false.
The Denver Post reported that McInnis used parts of a 1994 newspaper column he wrote from a column that appeared in The Washington Post six weeks prior.
Duffy told 9NEWS that McInnis' column for The Rocky Mountain News was written with the help of Daryl Plunk. Plunk is the same person who wrote the column in The Washington Post.
"So while some of the words there indeed are mine, they surely are not 'plagiarized,'" Plunk wrote in an e-mail to The Denver Post on Wednesday. "I was very pleased and proud to have advised and assisted Congressman McInnis on those two straight-forward policy analyses."
Earlier McInnis told The Associated Press, "In Congress, you have lots of staff. I had hundreds of pages a day go out of my congressional office with my signature on it. We have no idea of the base material."
"Of course I had assistants writing that," McInnis added.
Duffy says this second allegation of plagiarism is false because "you can't plagiarize yourself."
"[I] just think people need to take a breath and listen to the facts, and in this case, we're very disappointed that the largest paper in the state was hell bent to get something in the press that validated what they believed was a theory," Duffy said. "Now we're having to un-ring a bell and that's tough to do. They had that on page one this morning. Are they going to put the truth on page one tomorrow morning?"
The Denver Post says it repeatedly tried to contact the McInnis campaign about the latest allegation on Tuesday before the story went to press.
"We offered the candidate every opportunity to explain the circumstances of how the duplication occurred," Denver Post Editor Greg Moore said in an e-mail. "We told Mr. McInnis that he could contact me directly last evening to discuss the story and he never did. We would have been happy to publish whatever explanation they offered. We were unable to contact the authors of the original op-ed yesterday but had we been able to we would have included their response in this morning's article. None of that would have changed our decision to publish, however, or the general focus of the story. As we continue reporting this story, the McInnis campaign will continue to be solicited for comment pre-publication. I hope they take advantage of that."
Meanwhile, Democratic leaders such as Colorado House Speaker Terrance Carroll have called for McInnis to withdraw from the governor's race.
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