Stephanie Taylor, the co-founder of Progressive Change Campaign Committee, fretted that Kaine’s support of a pending trade deal known as the Trans-Pacific Partnership could allow Republican presidential nominee Donald Trump to “outflank” Clinton on trade.

Trump has been trying to reach out to Sanders supporters and blue collar Democrats, arguing that his protectionist views are more in line with theirs than those of the presumptive Democratic nominee.

“It’s now more important than ever that Hillary Clinton run an aggressive campaign on core economic ideas like expanding Social Security, debt-free college, Wall Street reform, and yes, stopping the TPP,” Taylor said. “It’s the best way to unite the Democratic Party, and stop Republicans from winning over swing voters on bread-and-butter issues.

On Thursday, as speculation was mounting that Kaine would be Clinton’s choice, Charles Chamberlain, executive director of the activist network Democracy for America, which backed Sanders in the primaries, said that it should be “disqualifying” for any potential Democratic vice-presidential nominee to “help banks dodge consumer protection standards”.

That was based in part on a bipartisan letter that Kaine signed on Monday urging the Consumer Financial Protection Bureau to “carefully tailor its rulemaking” regarding community banks and credit unions so as not to “unduly burden” these institutions with regulations aimed at commercial banks.

On Friday, Norman Solomon, the coordinator of a group billing itself as the Bernie Delegates Network, called Kaine “a loyal servant of oligarchy”.

“If Clinton has reached out to Bernie supporters, it appears that she has done so to stick triangulating thumbs in their eyes,” said Solomon, whose organisation claims to represent hundreds of Sanders delegates attending the convention in Philadelphia but is not coordinating with the campaign.

The group has threatened to protest during the Democratic convention with Kaine on the ticket.

Winnie Wong, an Occupy Wall Street veteran who founded the group People for Bernie, was also underwhelmed with Kaine’s pick, calling it “unsurprising and predictable”.

“It shows a woeful disregard to the progressives who fought so hard this year to create conditions for transformational change this country desperately needs,” Wong said. “Team Clinton did the math on this horse race and they are betting on Tim Kaine to court those white male moderate/indy voters who won’t vote for her. I doubt they can be moved.”

Kaine’s selection was touted by other traditional boosters of the Democratic Party, including several labour union leaders.

Marc Parrone, president of United Food and Commercial Workers Union, praised Kaine for a long record of having “supported hard-working families and worked to make their lives better.”

“When a plan to sell grocery stores in Virginia was announced earlier this year, threatening the livelihoods of hundreds of UFCW families, Senator Kaine stood with us as we successfully rallied the community to save local jobs.” Parrone said.

Meanwhile, Mary Kay Henry, president of the Service Employees International Union, called Kaine “an experienced leader with a proven track record on issues from raising wages to immigration reform and racial justice”.

In picking Kaine, Clinton passed over two Hispanic candidates who were considered, Housing Secretary Julián Castro and Labour Secretary Thomas Perez.

Though many Latino leaders were disappointed, a leading group praised Kaine as “no stranger to the Latino community,” citing the time he spent as a missionary in Honduras.

“He has consistently put emphasis on communicating with our community, hearing and addressing their concerns,” said Pili Tobar, advocacy and communications director for Latino Victory Fund.