BRUSSELS - Scotland's senior politician in Europe David Martin MEP has cast doubt on completion of a Transatlantic Trade and Investment Partnership (TTIP) deal in the lifetime of the current European Parliament or the Obama administration.

The veteran MEP is coordinator of the European Parliament's centre left bloc the S&D (Social & Democrats) on the international trade committee. His remarks are also likely to be influential because of his 30 years experience in the parliament, and because he himself is an outspoken supporter of the controversial US-EU TTIP deal.

Advocates of a comprehensive trade facilitation agreement between the world's two largest trading blocs, which include the UK and Scottish Governments, claim that the prospective regulatory convergence and tariff-reduction deal could deliver a £10bn a year boost to Britain's economy or £100bn across Europe.

In remarks to international journalists during the 10th round of US-EU negotiations last week he said: "I am now pretty convinced that this European Parliament [which will last until 2019] will not vote on TTIP. The negotiations will be long and hard, as its the sheer scale of the agreement that makes it so attractive as well as frightening."

"We've never had such public interest in trade policy before and if that continues, I don't know how it will impact the deal. You can always find a reason to be against any trade agreement."

TTIP supporters concede that the European Commission and the Obama administration were initially wrong-footed by the strength of the political and NGO opposition to what is a highly technical trade deal, and have spent much of the last year struggling to regain the initiative, largely through the efforts of the new trade Commissioner Cecelia Malstroem.

The Swedish politician was tasked last year by Commission President Jean Claude Juncker to bring about a "fresh start" for TTIP, leading her to usher in a degree of transparency unprecedented in trade negotiations, where practitioners are habitually secretive their negotiating documents and positions.

Insiders now admit that the deal's promoters were wrong to present the deal as a "revolutionary", and now presenting TTIP as the natural extension of the "shared values" of the two giant trading entities, who exchange transatlantic trade in goods and services worth €26bn (£18bn) a day, and which have $4 trillion (£2.5tr) in total investments in each others' economies.

Both sides want business to take more of a lead in promoting the potential benefits of a comprehensive TTIP agreement, and have been talking up "accelerated" progress to catch the current "window of opportunity" before November 2016. At that point the US presidential election, the change of administration and appointment of new officials in Washington will put meaningful progress on ice for an extended period.

One official close to the talks told The Herald: "There is not much in the way of low-hanging fruit, all of the easy stuff has been done. We must make progress on all the issues, and we all understand that we need to deal with the major concerns. If issues aren't addressed, an agreement won't pass the national parliaments."

Prime Minister David Cameron last week conceded that the agreement faced “a big fight” to overcome sustained attacks, warning that Britain would “rue the day if we miss this opportunity” to open up transatlantic markets.

Cameron said: “I am hugely positive about it but I think we have a big fight to win because the left across Europe is mobilising, often through NGOs, to try to find all sorts of reasons why this is a bad idea,”

“But when you examine them – whether it is the idea we are all going to be force-fed chlorinated chickens or have American banks buy up our health service - they all fall apart.

“There is no question: the National Health Service will remain a national health service and in terms of these investor dispute resolution mechanisms, we have signed them into all the trade deals we’ve ever done and we’ve never lost a single case.

In Scotland, where the US is the single largest overseas export destination, support for TTIP has been led by business organisations including the British-American Business Council, CBI Scotland and the FSB Scotland, as well as individual businesses with an interest in expanding markets in the US.

Keith Neilson of Craneware, the Scottish medical software company that last week announced record sales of $72.5 million (£46.5m) to US healthcare providers, has said that a successful TTIP agreement "could mean we are able to trade with the US more efficiently, helping to strengthen and align intellectual property rights for the transatlantic market.

Another Scottish exporter, Jonathan Kay of Edinburgh-based Big Cheese Making Kit said that lack of a comprehensive agreement aligning regulation and standards there are additional costs, extra paperwork and many decisions... [the absence of a TTIP deal] simply makes expansion' more difficult than it needs to be."

TTIP has received a double boost in recent weeks most recently from a European Parliament resolution earlier this month giving strong backing to negotiations. In June the Republican-dominated Congress granted President Obama "fast track" authority to negotiate what he hopes will be his legacy trade agreements, the Trans Pacific Partnership (TPP) and TTIP.