JPMorgan Chase shareholders approved a controversial $20 million pay package for chief executive Jamie Dimon Tuesday, although fewer than two-thirds voted in favor.

Support for the bank's executive compensation plan was 61 percent, according to preliminary results released at JPMorgan's annual meeting in Detroit.

That is below the 77.9 percent support for the compensation package in 2014 and 92.4 percent in 2013.

Dimon's 2014 compensation was the same overall level as in 2013, but the structure of the package came in for criticism from shareholder advisory firms Institutional Shareholders Services and Glass Lewis.

The two objected to the inclusion of a $7 million cash incentive bonus in the pay package, which replaced Dimon receiving comparable pay in stock during the last two years.

JPMorgan said the cash award "reflects the board’s desire to return Mr. Dimon’s pay mix to market-competitive levels," and the board said his compensation overall was appropriate given the bank's strong performance.

But ISS said substituting cash for stock eliminates an executive retention incentive, adding that the size of the award "appears arbitrary."

"While provision of cash incentives to top executives is standard compensation practice, the lack of strong rationale for reverting to substantial cash awards that have no connection to attainment of preset goals raises significant concern," ISS said.

In another sign of greater disenchantment of investors, a significant minority of shareholders (36 percent) also supported a proposal backed by ISS and Glass Lewis to require an independent chairman for the bank once Dimon retires.

Dimon is one of a handful of chief executives at large banks who also serves as chairman.

Critics say the presence of a chairman independent of the CEO would guard against conflicts of interest and ensure stronger risk-management.

The board had defended the dual roles for Dimon as the best structure under the circumstances, and said it could change course down the road as needed.

JPMorgan reported $21.7 billion in earnings in 2014, up 21.4 percent from the prior year. However, the bank has continued to rack up huge legal bills which have hit shareholder returns.

On Wednesday, it is expected to join four other banks in a criminal settlement of charges it conspired to rig the foreign exchange market. Combined penalties on the five banks are expected to total in the billions of dollars.