"I'd like nothing more for the establishment to count us out," O'Rourke told CNN in a phone interview from El Paso.
The 44-year-old third-term House Democrat isn't hiring pollsters or campaign consultants and is sticking with a pledge he made during his first run for the House to refuse any corporate money or donations from political action committees. He pointed to his party's dismal record in the last 30 years trying to win a Senate seat in Texas, saying Democrats spent close to a billion dollars on "consultants, polls, wizards and experts, and we really came up short."
O'Rourke insisted that his retail strategy to travel the state is "not complicated" and made it clear he doesn't think much of targeted data-driven campaigns, saying, "I'm going back to the basics." He said he could try the same playbook that other Democratic statewide candidates like former state Sen. Wendy Davis tried, or "I can run an honest campaign about Texas, driven by Texas."
Cruz didn't respond directly to O'Rourke's argument that the senator has been too focused on national politics, but said in a written statement to CNN that he "will continue to work every day to earn and keep the trust of Texans across our great state. I'm confident that Texans want a senator who will lead the fight for freedom -- defending the Constitution, getting government off our backs, and allowing small businesses to create jobs and opportunity."
The National Republican Senatorial Campaign Committee was more direct about O'Rourke, saying he's out of step with the state.
"Beto O'Rourke would be a shoo-in for the United States Senate if he was running in Massachusetts or California -- his voting record is perfect for those states," committee spokeswoman Katie Martin told CNN in a written statement.
O'Rourke, who once traveled the country in a punk rock band, now represents the far-western corner of the state along the southwest border. He officially announced his campaign in his hometown of El Paso on Friday, saying, the state needs "a senator who is not using this position of responsibility and power to serve his own interests, to run for president, to shut down the government."
Cruz was among those Republicans arguing that a must-pass spending bill in 2013 strip funding for Obamacare, and the standoff with the White House over the issue triggered a 16-day shutdown when federal agencies didn't have funding.
When told that the other Texas Republican senator, John Cornyn, told Politico earlier this week that his campaign amounted to a "suicide mission," O'Rourke seemed unfazed by the description, saying he has "a tremendous amount of respect" for Cornyn and they've worked on some issues together.
O'Rourke said on a personal level Cruz is a "nice guy," although he doesn't know him well. He noted that the GOP senator doesn't have an office in his district near the border, and said he approached Cruz during the 2013 fight over federal funding that resulted in a shutdown to appeal to him to back down because border agents and other federal employees were affected by the shutdown.
Before O'Rourke can train his focus on Cruz, however, he might need to clear a primary fight. Rep. Joaquin Castro, whom O'Rourke phoned to tell him he was announcing his bid, is also considering the Senate race. O'Rourke said his colleague would make "a great candidate, and I'm a fan of his, a friend of his," but when asked how he could prevail over him in a potential matchup, O'Rourke replied: "I don't know."
The Democratic Senatorial Campaign Committee so far isn't weighing in, instead deciding to focus on protecting incumbent senators in states Trump won in 2016, such as North Dakota, Missouri, and Indiana. The party faces tough odds of retaking the chamber; although the GOP holds a narrow, 52-48 majority, Democrats will have to defend 25 of the 33 contests in the 2018 midterms, including the two independents who caucus with the party, Maine's Angus King and Vermont's Bernie Sanders.
But aides at the Senate Democrats' campaign arm tell CNN they are monitoring the Texas race.
Both O'Rourke and Castro speak highly of each other, but cut different profiles in the House Democratic caucus. O'Rourke noted he voted against House Minority Leader Nancy Pelosi and said he is "fiercely independent," while Castro helps the leadership team corral votes and has been given a coveted seat on the House intelligence committee.
Castro told CNN earlier this week that O'Rourke's move doesn't change his plans to continue looking at the race, and he's sticking with a timeline to make his decision sometime in April.
Meanwhile, the dynamic that Democrats want to highlight is Cruz's own split with the President during the contentious GOP presidential primary.
"Here are some words we almost never say: Donald Trump was right -- about 'Lyin Ted,'" David Bergstein, spokesman for the Democratic Senatorial Campaign Committee, told CNN. "Texans know Ted Cruz is a self-serving politician, and this campaign will spotlight the many ways in which he's only ever looking out for himself,"
In El Paso on Friday, O'Rourke said that even those he meets across the state who voted for Trump say they want someone in the Congress who will be willing to break through partisan sniping and get things done.
But O'Rourke acknowledged that people are saying the same things now that they said about his first run for his congressional seat.
"I know a lot of people feel this is impossible," he said, but he dubbed El Paso, where he began a tour around the state, "an underdog city."