The freshman senator from Texas has never shied from attacking the men and women whom he works alongside each day. But Cruz, lodged in the middle of the 2016 GOP presidential pack, is taking his criticism of fellow Republican senators to a new level — rhetorically and in his new book out Tuesday, “A Time for Truth.”

Cruz accuses McConnell and GOP leadership of maneuvering to dry up his fundraising and plant hit pieces in the press aimed at hurting him politically. He says GOP leaders cowered from joining him in big fights over the debt ceiling, Obamacare and gun control, accusing his colleagues of “mendacity” and capitulating to Democrats to avoid bad headlines.

He contends that McConnell misled him in vowing to stay out of primaries when Cruz accepted a senior-level position at the National Republican Senatorial Committee. And he accuses a GOP rival, Rand Paul of Kentucky, of parroting McConnell’s talking points by seeking to “undermine” his efforts to defund Obamacare during the 2013 fight that led to the government shutdown.

“During my time in the Senate, I’ve been amazed how many senators pose one way in public — as fiscal conservatives or staunch tea party supporters — and then in private do little or nothing to advance those principles,” Cruz writes in his 342-page book.

Disparaging Washington, of course, is one of the more timeworn campaign tactics of presidential hopefuls. What’s less typical is the personal, pointed way Cruz is doing it as his campaign ramps up. He’s leaning heavily into his brand of unapologetic and confrontational conservatism, arguing that GOP leadership’s compromises with Democrats are nothing more than “surrender.”

Yet presenting himself as a polarizing figure at war with the party establishment is a risky way to try to become the Republican presidential nominee. Plus, Republicans are beginning to undercut several of Cruz’s assertions, including over his role at the NRSC, which received a giant donation from the senator’s campaign committee last fall, despite his sharp criticism of the group in his book.

Cruz’s book is in keeping with his stepped-up effort in recent days to portray himself as the one GOP candidate who’s taken on party leadership. On the Senate floor last week, he accused unnamed Republicans of “quietly celebrating” the Supreme Court’s decision to uphold Obamacare subsidies. After vocally endorsing trade legislation backed by party leaders, Cruz flipped on the issue, bemoaning in an op-ed “corrupt” Washington deal making on the matter and singling out McConnell and House Speaker John Boehner for misleading conservatives.

And in the opening chapter of his book, Cruz calls out McConnell and his GOP colleagues for “chicanery” by publicly opposing an increase in the borrowing limit while privately trying to let the debt ceiling increase in 2014 without their fingerprints. When he told a California GOP donor in 2014 about the debt ceiling dispute, Cruz recalls the donor saying repeatedly: “The bastards.”

“In the 2016 primary, you’re going to have 15 candidates up there going, ‘I’m conservative. No, no, I’m conservative.’ And what we see is they go to Washington and they don’t do what they said they would do,” Cruz told NPR Monday in an interview about his book. “I think the question Republican primary voters should ask is, ‘When have you stood up against the Washington cartel? When have you stood up against leaders in our own party?’”

Don Stewart, a McConnell spokesman, declined to comment.

Since coming to Washington in 2013, Cruz has co-sponsored only three bills that have become law, none of them controversial. But in his book, Cruz suggests that cutting deals to pass legislation shouldn’t be the gauge of senatorial success.

“Sometimes, people ask me, ‘When you have a room full of Republican senators yelling at you to back down and compromise your principles, why don’t you just give in?’” Cruz wrote. “The answer is simple. I just remember all those men and women who pleaded with me, ‘Don’t become one of them.’”

In his book, Cruz writes that immediately after he won his 2012 Senate race, McConnell made a “concentrated effort to befriend me.” Cruz said he was “wary,” but “glad to reciprocate.” He joined McConnell on an official trip to Afghanistan and Israel and was the GOP leader’s guest at the 2013 Alfalfa Club Dinner. McConnell awarded Cruz with plum committee assignments — even a spot on the Senate Rules Committee, which is typically reserved for more senior members.

As an added bonus, McConnell named him vice chairman of the NRSC, the main committee aimed at protecting incumbents and winning Senate seats for Republicans. In Cruz’s telling, McConnell wanted to enlist Cruz as an emissary to the tea party and had “promised that the committee would stay out of primaries from here on out.”

When the NRSC began to back GOP incumbents in contested primaries, and help other Republicans it favored in open seats, Cruz said he “stopped asking donors to support” the committee.

“It was yet another lesson: Assurances in Washington come with an expiration date.”

Josh Holmes, a former chief of staff to McConnell, questioned the accuracy of Cruz’s recollection of the episode.

“I don’t recall any misunderstandings at the time Sen. Cruz agreed to serve about Leader McConnell’s view that the first job of the NRSC is to protect incumbent Republicans in primary and general elections,” Holmes said. “As any casual observer will recall, McConnell was not exactly shy about expressing himself publicly and privately on this topic, and until today, I’ve never heard of anyone who was unclear about his position.”

According to documents obtained by POLITICO, Cruz’s decision to transfer $250,000 to the committee in September — during general election season — tied him for second most among all GOP senators last cycle. Moreover, Republican sources said that Cruz was in regular communication with senior NRSC staff about where he could play a role to help GOP candidates in the heat of fall campaign.

But a chunk of the book focuses on Cruz’s war with his colleagues.

Cruz, a Harvard Law graduate and former Texas solicitor general, says many of his colleagues lack a background of a litigator and let witnesses off the hook during oversight hearings. “Unfortunately, many senators are wholly untrained in this area.”

After he was sworn into office in 2013, Cruz made his mark early on during confirmation hearings over Chuck Hagel’s nomination to be secretary of defense, even suggesting that the former Nebraska senator may have benefited financially from extremist groups and hostile nations, such as North Korea.

While Cruz writes in his book, “I made a mistake when I uttered the words North Korea,” he said that Hagel was not forthcoming about a gap in his finances and said the nominee was aided by “media complicity.”

“The media’s personal attacks on me were a sign of things to come,” Cruz said.

Indeed, Cruz doesn’t hide his contempt for the press, accusing McConnell’s team of going to POLITICO and The Wall Street Journal editorial pages with negative stories about him. This — compounded with what he said were threats from GOP leaders to K Street and big-spending political action committees not to help him out — were meant to send him a message, Cruz wrote.

Cruz said “once I demonstrated that I would stand up to party leadership,” members of the GOP leadership warned K street and PACs they would be “frozen out” if they continued to support him.

McConnell and Cruz’s relationship took a hit in May 2013 when the Texas freshman refused to allow House and Senate negotiators to meet for conference negotiations on the budget. He believed they would use it as a backdoor way to raise the debt ceiling. It went further south that fall when Cruz demanded that any spending bill to keep the government open also include provisions to defund the health care law — a dispute that led to the 16-day government shutdown.

What made things worse was that Cruz helped raise money for the Senate Conservatives Fund, a group trying to defeat GOP senators like McConnell in primaries. (After the shutdown, Cruz privately told hiscolleagues he would no longer fundraise for SCF.)

Cruz bashes his colleagues for their unwillingness to join his push to defund the health care law, many of whom saw it as a poorly conceived idea that had no chance of success.

“Imagine what would have happened if the Republican Senate leadership had simply decided … let’s support House Republicans,” Cruz said. If Cruz had just listened to GOP Senate leaders, he wrote: “We will never stop Obamacare. .. At every stage, their plan was to avoid the fight.”

To make his point, Cruz launched a floor speech for 21 straight hours in late September 2013. During the marathon speech, Cruz said he and Utah Sen. Mike Lee were surprised that Paul seemed intent on hurting his effort.

“Another tea party senator was notably less helpful,” Cruz wrote. “My friend Rand Paul came to the Senate floor to ask questions that seemed deliberately designed to undermine our efforts. … His questions echoed the skeptical attacks of Mitch McConnell, and I marveled that Rand had decided not to be with us in this fight.”

“Mike Lee is not an easily excitable guy, but he was so upset by this that I thought he was going to need a sedative.”

Aides to Lee and Paul both declined to comment.