The Associated Press’ Liz Sidoti:

As a candidate, Barack Obama vowed to bring a different, better kind of leadership to the dysfunctional capital. He’d make government more efficient, accountable and transparent. He’d rise above the “small-ball” nature of doing business. And he’d work with Republicans to break Washington paralysis.

You can trust me, Obama said back in 2008. And – for a while, at least – a good piece of the country did.

But with big promises often come big failures – and the potential for big hits to the one thing that can make or break a presidency: credibility.

A series of mounting controversies is exposing both the risks of political promise-making and the limits of national-level governing while undercutting the core assurance Obama made from the outset: that he and his administration would behave differently.

The latest: the government’s acknowledgement that, in a holdover from the Bush administration and with a bipartisan Congress’ approval and a secret court’s authorization, it was siphoning the phone records of millions of American citizens in a massive data-collection effort officials say was meant to protect the nation from terrorism. This came after the disclosure that the government was snooping on journalists.

Also, the IRS’ improper targeting of conservative groups for extra scrutiny as they sought tax-exempt status has spiraled into a wholesale examination of the agency, including the finding that it spent $49 million in taxpayer money on 225 employee conferences over the past three years. …

Even Democrats are warning that more angst may be ahead as the government steps up its efforts to implement Obama’s extraordinarily expensive, deeply unpopular health care law.

Collectively, the issues call into question not only whether the nation’s government can be trusted but also whether the leadership itself can. All of this has Obama on the verge of losing the already waning faith of the American people. And without their confidence, it’s really difficult for presidents to get anything done – particularly those in the second term of a presidency and inching toward lame-duck status.

The ramifications stretch beyond the White House. If enough Americans lose faith in Obama, he will lack strong coattails come next fall’s congressional elections. Big losses in those races will make it harder for the Democratic presidential nominee in 2016, especially if it’s Hillary Rodham Clinton, to run as an extension of Obama’s presidency and convince the American public to give Democrats another four years. …

A Quinnipiac University poll conducted late last month found 49 percent of people consider Obama honest and trustworthy, a dip from the organization’s last read on the matter in September 2011 when 58 percent said the same. He also has taken a hit among independents, which used to be a source of strength for him, since his second-term controversies have emerged. Now just 40 percent say he is honest and trustworthy, down from 58 percent in September 2011.

Obama has waning opportunities to turn it around. He’s halfway through his fifth year, and with midterm elections next fall, there’s no time to waste.

If he can’t convince the American people that they can trust him, he could end up damaging the legacy he has worked so hard to control and shape – and be remembered, even by those who once supported him, as the very opposite of the different type of leader he promised to be.

The American people should not have trusted Obama in the first place. But hey, better late than never.