After a torrent of poor headlines in recent days, Republican presidential hopeful Mitt Romney sought to go on the offensive Sunday, attacking Barack Obama's over "policy failures" and his perceived coolness towards Israel.

In a tweet sent to some 700,000-plus followers, Romney criticised Obama for not visiting the middle eastern country during his near-four years in office, adding: "We need a leader who stands with our allies".

It comes a week after the Republican challenger caused anger amongst Palestinians during a visit to the region by suggesting that Israel's economic dominance was due to a superior culture and the "hand of providence".

In a campaign ad linked to in the tweet, Romney is seen speaking in Jerusalem, "the capital of Israel" he says, in a further overture towards the pro-Israeli lobby in the US.

The attack on the White House's perceived stance on Israel has been a constant in the Republican election campaign.

In the primary season, Obama was accused by rivals for the GOP candidacy of presiding over a policy of "appeasement" in regards to the Palestinians.

Meanwhile, Romney has previously accused the president of throwing Israel "under the bus".

In a further bid to steal back political initiative after being hammered over missteps during his first overseas trip as candidate and his refusal to release further tax returns, Romney tore into the administrations record on Saturday, attacking what he called "an extraordinary series of policy failures".

While on the stump in Indiana, the former Massachusetts governor seized on the latest jobs report as evidence that his Democratic opponent's economic policies aren't working.

On Friday, it emerged that the American economy added 163,000 jobs in July, the best pace of hiring in five months.

But even so, the jobless rate ticked up to 8.3% from 8.2% in June.

"These are real families having real hard times," Romney told supporters. "This has been an extraordinary series of policy failures on behalf of the president," he added.

But despite his efforts to change the political narrative, issues of personal tax continued to dog the Republican this weekend.

On Thursday, Senate leader Harry Reid accused Romney of not paying tax for a decade, and challenged the White House hopeful to publish more of his annual returns to the IRS to prove him wrong.

The former Massachusetts governor angrily decried Reid's comments, telling him to "put up" his source, or "shut up".

"I have paid taxes every year, and a lot of taxes. So Harry is wrong," he said on Friday.

But Democrats sought to keep up the heat on Romney in regards to his tax arrangements on Sunday.

Speaking on CNN's State of the Union, senior Obama aide Robert Gibbs said: "Have you ever seen anybody go to such lengths to not put something out? And when you generally don't put something out, isn't it because you're generally hiding something?"

So far Romney has refused to release any more tax records other than the two years' worth he made public back in January.

Those documents revealed that the former Massachusetts governor and his wife recorded an income of $21.6m in 2010. Of that, they handed over $3m in tax at a rate just shy of 14%.

The couple's effective tax rate is expected to increase a little on 2011's earnings, when they are expected to pay 15.4% on $20.9m. On both years the rate of tax paid is far lower than the average American.

Gibbs told CNN that if the Republican candidate had nothing to hide, he should release more documents. He even joked that he would lend Romney the money to get the paperwork copied.

"I'll send him the nickels," the Obama aide said, adding: "I think it's a nickel a page".