Mitt Romney campaigns at Acme Industries in Elk Grove Village, Ill.,on Aug. 7. (Charles Dharapak/AP)

Mitt Romney’s favorability ratings have stalled over the course of his campaign’s bumpy summer months, with his earlier improvements as he was wrapping up the Republican nomination in the spring appearing to flat-line, according to a new Washington Post-ABC News poll.

While 40 percent of voters now say they hold a favorable opinion of the former Massachusetts governor — virtually unchanged from May — those holding negative views of Romney ticked higher in the new poll, from 45 percent to 49 percent.

Meanwhile, President Obama remained in positive territory on that measure, with 53 percent of voters reporting they hold favorable opinions of the incumbent. Only 43 percent say they feel unfavorably toward him.

Polls have generally shown a tight contest despite Obama’s consistent edge on the question of personal popularity.

But a Post poll concluded just as Romney was clinching the nomination showed Romney appearing to gain ground on the president. His favorability ranking rose to a career best 41 percent, while for the first time he matched Obama among detractors, with 45 percent viewing each man unfavorably.

Romney’s failure to gain on Obama since then may be a sign that his image has been damaged by summer stumbles, including new attention on Romney’s tax returns and an overseas trip that included well publicized gaffes.

The numbers could increase pressure on Romney to find a way to connect personally with voters at the Republican National Convention later this month.

Critically, independent voters now hold their favorable views of Obama more strongly than of Romney. More independents view Obama favorably than unfavorably, by a 53 to 40 percent margin. Their opinions of Romney were nearly reversed, with 37 percent viewing him favorably and 50 percent unfavorably.

And while Republicans may be warming to Romney — 83 percent now feel positively toward him, his highest measure yet — only 41 percent feel “strongly favorable” about him. Meanwhile, 61 percent of Democrats feel strongly favorable toward their candidate, with 84 percent holding overall positive impressions.

The poll was from Aug. 1 to Aug. 5, among a random national sample of 1,026 adults. The margin of sampling error for the full poll is plus or minus four percentage points.

Romney’s unfavorability rate is rising among Democrats. What does this say about the presidential race?