Disapproval of President Obama’s handling of the economy is heading higher — alongside gasoline prices — as a record number of Americans now give the president “strongly” negative reviews on the 2012 presidential campaign’s most important issue, according to a new Washington Post-ABC News poll.

Increasingly pessimistic views of Obama’s performance on the economy — and on the federal budget deficit — come despite a steadily brightening employment picture and other signs of economic improvement, and they highlight the political sensitivity of rising gas prices.

The potential political con­sequences are clear, with the ­rising public disapproval reversing some of the gains the president had made in hypothetical general-election matchups against possible Republican rivals for the White House. Former Massachusetts governor Mitt Romney and former senator Rick Santorum (Pa.) now both run about evenly with Obama. The findings come just five weeks after Obama appeared to be getting a boost from the improving economy.

Gas prices are a main culprit: Nearly two-thirds of Americans say they disapprove of the way the president is handling the situation at the pump, where rising prices have already hit hard. Just 26 percent approve of his work on the issue, his lowest rating in the poll. Most Americans say higher prices are already taking a toll on family finances, and nearly half say they think that prices will continue to rise, and stay high.

Friday’s employment report showed a gain of 227,000 jobs in the past month, continuing an upward trend and offering the White House something positive to point to. Still, the survey — conducted Wednesday through Saturday — finds 59 percent of Americans giving Obama negative ratings on the economy, up from early last month. Now, 50 percent give him intensely low marks, the most yet in a Post-ABC News poll, and a jump of nine percentage points.

The negative movement has also stalled what had been a gradual increase since the fall in the president’s overall approval rating. In the new poll, 46 percent approve of the way Obama is handling his job; 50 percent disapprove. That’s a mirror image of his 50 to 46 positive split in early February. The downshift is particularly notable among independents — 57 percent of whom now disapprove — and among white people without college degrees, with disapproval among this group now topping approval by a ratio of more than 2 to 1, at 66 versus 28 percent.

These groups are also the ones whose shifting support has re-shuffled prospective general-election matchups. Among registered voters, Obama is now on par with Romney (47 percent for the president, 49 percent for Romney) and Santorum (49 to 46 percent). Previously, Obama held significant advantages over both.

The Republican presidential race is now a contest between Romney and Santorum. Among Republicans and GOP-leaning independent voters, 33 percent favor Romney for the nomination; 29 percent prefer Santorum. This is the first Post-ABC poll after Santorum’s emergence as a top-tier candidate. Trailing the top two are former House speaker Newt Gingrich (Ga.) at 14 percent and Rep. Ron Paul (R-Tex.) at 12 percent.

The poll offers some conflicting evidence about the president and the still flagging national economy. In addition to low ratings on his handling of gasoline prices, Obama’s approval rating on the deficit hit an all-time low, with a slender 32 percent giving him positive marks. Among independents, 70 percent disapprove here, also a new high.

Even on foreign policy — a onetime strong point — Obama’s ratings look worse. For the first time in nearly a year, as many Americans disapprove as approve of his handling of the war in Afghanistan. On Iran, a slim majority now disapproves of how he is dealing with the possibility of the country obtaining nuclear weapons.

On energy issues generally, almost half the country gives Obama negative marks. Republican candidates have hammered the president on this, arguing that his policies have contributed to the rise in gasoline prices. Fifty percent of Americans see the Obama administration as having the power to do something about the cost of a gallon of gasoline; 45 percent say the administration has no such control.

Higher gasoline prices are falling harder on certain groups than others. Those with yearly household incomes below $50,000, non-whites and whites without college degrees are among the most likely to say the rise in prices has caused serious economic hardship. But there appears to be an ideological aspect to the responses as well, with Republicans and strong supporters of the tea party movement more likely to say they are feeling a financial pinch than those in the president’s base.

For Obama, not all signs are negative when it comes to the economy. As many now see reason for economic optimism as pessimism, and two-thirds are bullish on their own prospects. Nearly half now say they sense that an economic recovery is underway, up significantly from early fall.

More significantly, perhaps, as many now say the president’s economic program is making things better as say it is making things worse, a clear shift over the past six months. Romney and other Republicans have long argued that Obama’s policies lengthened the recession and have slowed the recovery.

The bulk of each of these positive shifts for the president comes from improving views among Democrats, suggesting a strengthening of his base, not a broadening of his appeal to independents or Republicans.

If the economy offers perils and opportunities for Obama, there is another area where he and his party can boast a clear advantage over Republicans. By a wide margin of 55 percent to 30 percent, Americans see the Democrats as the ones who care more about issues of particular importance to women. Majorities of women and men both share this view.

Public assessment of the parties on gender-specific issues is similar to what it was in 2000, and also reflects current divisions in the fight over funding of contraception. Most Americans — 61 percent — say health insurance companies should be required to cover the full cost of birth control for women; 35 percent disagree.

At the same time, support for complete contraceptive coverage declines when the issue of religion is factored into the decision. Asked about employers who have religious objections — including affiliated hospitals and schools — support is more evenly divided.

Democrats also hold a double-digit advantage in being perceived as having greater concern for people’s problems, and a five-point edge on better representing respondents’ personal values.

As the Republican race heads toward two big primaries in Alabama and Mississippi on Tuesday, Republicans nationally say, by a significant margin, that they have more confidence in Romney to deal with the economy over both Gingrich and Santorum. On social issues, Santorum enjoys greater trust over Romney and Gingrich.

Santorum and Romney are rated almost equally on who best reflects the party’s core values, but Romney continues to hold a huge advantage on the question of who can beat Obama in November. By an even greater margin, Romney is seen as the likely winner of the party’s nomination.

Obama’s team may take comfort, however, that, notwithstanding the tightness of the general-election race today, a majority of Americans now say they believe he will win reelection in November.

The telephone poll was conducted March 7-10, among a random national sample of 1,003 adults. Results of the full poll have a margin of sampling error of plus or minus four percentage points.

Polling manager Peyton M. Craighill and polling analyst Scott Clement contributed to this report.