WASHINGTON (Reuters) — With his Iraq strategy mired in chaos, his inner circle besieged and a hostile Congress asserting itself, there is still one thing President George W. Bush can depend on — his own refusal to bend.Even with fellow Republicans increasingly questioning the wisdom of his policies, he shows little sign of wavering, reflecting a single-mindedness that has become a defining trait of his presidency.

Bush’s supporters call it the mark of a principled leader, while critics see it as symptomatic of a reckless worldview that mistakes intransigence for resolve.

What it means in practical terms, however, is no end in sight to political gridlock in Washington.

The president’s veto on Tuesday of legislation that would have imposed a timetable for U.S. troop withdrawal from Iraq could be the first of many legislative standoffs to come in his final 21 months in office.

“George W. Bush is of a mind-set that says, ‘You’re not going to tell us what to do,’” said Shirley Anne Warshaw, a presidential scholar at Gettysburg College in Pennsylvania. “The ‘decider’ still hasn’t learned to be the compromiser.”

And compromise isn’t going to get any easier.

Facing a Democratic-led Congress challenging his conduct of the war and using its broad authority to investigate his administration, Bush is digging in his heels even harder as he fights to stave off lame-duck status.

He is also defying calls to dump Attorney General Alberto Gonzales over the botched firing of federal prosecutors, and to withdraw support for Paul Wolfowitz, an Iraq war architect now embroiled in scandal as president of the World Bank.

In defending his loyalists, Bush is signaling how far he is willing to go to avoid the message of weakness that their forced departure might send, analysts say.

Adding to Bush’s pressures, a new book by former CIA chief George Tenet accuses administration officials of going to war in Iraq without “serious debate” on whether Saddam Hussein posed an imminent threat. The White House denies the charge.

But Bush seems to take pride in shrugging off such problems. Barred by law from seeking a third term, he also appears more than willing to buck public opinion.

He comes across as almost unshakable is his belief that history will vindicate him for an increasingly unpopular war that has driven his approval ratings down into the mid-30 percent range and eroded U.S. credibility at home and abroad.

“You must have a set of principles that are firmly etched in your soul,” Bush said on PBS’ “Charlie Rose Show.”

Still, some analysts say Bush is not as inflexible as he might seem and that his second-term woes have been magnified by Iraq, the overarching issue of his presidency.

He has, for example, softened over time on immigration reform and domestic spying and recently turned more pragmatic in dealing with North Korea, a country he once shunned as a charter member of what he had branded the “axis of evil.”

“Is he stubborn? Certainly. Is he resolute? Yes,” said Stephen Hess, a political scientist at George Washington University. “But Iraq makes everything look worse than it is.”

Bush won his first term and then a second depicting his Democratic rivals as “flip-floppers” shifting with the political winds.

He was supposed to be the first “MBA president” <\m> he holds a masters of business administration from Harvard <\m> and would run the executive branch like a CEO, the conservative National Review magazine wrote in a scathing critique of Bush’s tenure.

But critics say instead of bringing management sense to the White House, he brought a rigid conservative agenda and surrounded himself with longtime lieutenants devoted to it.

Bush’s with-us-or-against-us approach helped galvanize the country in the aftermath of the Sept. 11 attacks. But his popularity fell as deteriorating conditions in Iraq turned most Americans against the war. That factored heavily into the Republicans’ loss of Congress in November’s elections.

Throughout his presidency, Bush has seemed loath to admit mistakes or change course, apparently seeing it as weakness. It is a lesson he may have learned from the fate of his father, who lost re-election after breaking his no-new-taxes pledge.

But single-mindedness has had its costs.

Bush kept Donald Rumsfeld as defense secretary long after even fellow Republicans were calling for his removal over his handling of the war, and then ousted him after the midterm elections when the political damage was already done.