Exhibit 14(a)

SUN LIFE ASSURANCE COMPANY OF CANADA (U.S.)

POWER OF ATTORNEY

I, Todd L. Boehly, hereby constitute and appoint Michael S. Bloom, Kenneth N. Crowley, Maura A. Murphy, and Christine McGeough, and each of them, my attorneys-in-fact, each with the power of substitution, for me in any and all capacities, to sign any Post-Effective Amendments to the Registration Statement of SUN LIFE ASSURANCE COMPANY OF CANADA (U.S.) (File No. 333-168712) under the Securities Act of 1933 and to deliver and file the same, with exhibits thereto, and other amendments in connection therewith, with the Securities and Exchange Commission, hereby ratifying and confirming all that each of said attorneys-in-fact or his or her substitute or substitutes may do or cause to be done by virtue hereof.

This power will expire no later than twelve months from date of execution.

IN WITNESS WHEREOF, I set my hand on the date shown.

/s/ Todd L. Boehly

Todd L. Boehly

Dated: August 3, 2013

Masters Flex II

SUN LIFE ASSURANCE COMPANY OF CANADA (U.S.)

POWER OF ATTORNEY

I, Mark R. Walter, hereby constitute and appoint Michael S. Bloom, Kenneth N. Crowley, Maura A. Murphy, and Christine McGeough, and each of them, my attorneys-in-fact, each with the power of substitution, for me in any and all capacities, to sign any Post-Effective Amendments to the Registration Statement of SUN LIFE ASSURANCE COMPANY OF CANADA (U.S.) (File No. 333-168712) under the Securities Act of 1933 and to deliver and file the same, with exhibits thereto, and other amendments in connection therewith, with the Securities and Exchange Commission, hereby ratifying and confirming all that each of said attorneys-in-fact or his or her substitute or substitutes may do or cause to be done by virtue hereof.

This power will expire no later than twelve months from date of execution.

IN WITNESS WHEREOF, I set my hand on the date shown.

/s/ Mark R. Walter

Mark R. Walter

Dated: August 3, 2013

Masters Flex II

SUN LIFE ASSURANCE COMPANY OF CANADA (U.S.)

POWER OF ATTORNEY

I, Dennis A. Cullen, hereby constitute and appoint Michael S. Bloom, Kenneth N. Crowley, Maura A. Murphy, and Christine McGeough, and each of them, my attorneys-in-fact, each with the power of substitution, for me in any and all capacities, to sign any Post-Effective Amendments to the Registration Statement of SUN LIFE ASSURANCE COMPANY OF CANADA (U.S.) (File No. 333-168712) under the Securities Act of 1933 and to deliver and file the same, with exhibits thereto, and other amendments in connection therewith, with the Securities and Exchange Commission, hereby ratifying and confirming all that each of said attorneys-in-fact or his or her substitute or substitutes may do or cause to be done by virtue hereof.

This power will expire no later than twelve months from date of execution.

IN WITNESS WHEREOF, I set my hand on the date shown.

/s/ Dennis A. Cullen

Dennis A. Cullen

Dated: August 3, 2013

Masters Flex II

SUN LIFE ASSURANCE COMPANY OF CANADA (U.S.)

POWER OF ATTORNEY

I, David E. Sams, Jr., hereby constitute and appoint Michael S. Bloom, Kenneth N. Crowley, Maura A. Murphy, and Christine McGeough, and each of them, my attorneys-in-fact, each with the power of substitution, for me in any and all capacities, to sign any Post-Effective Amendments to the Registration Statement of SUN LIFE ASSURANCE COMPANY OF CANADA (U.S.) (File No. 333-168712) under the Securities Act of 1933 and to deliver and file the same, with exhibits thereto, and other amendments in connection therewith, with the Securities and Exchange Commission, hereby ratifying and confirming all that each of said attorneys-in-fact or his or her substitute or substitutes may do or cause to be done by virtue hereof.

This power will expire no later than twelve months from date of execution.

IN WITNESS WHEREOF, I set my hand on the date shown.

/s/ David E. Sams, Jr.

David E. Sams, Jr.

Dated: August 3, 2013

Masters Flex II

SUN LIFE ASSURANCE COMPANY OF CANADA (U.S.)

POWER OF ATTORNEY

I, Ronald H. Friesen, hereby constitute and appoint Michael S. Bloom, Kenneth N. Crowley, Maura A. Murphy, and Christine McGeough, and each of them, my attorneys-in-fact, each with the power of substitution, for me in any and all capacities, to sign any Post-Effective Amendments to the Registration Statement of SUN LIFE ASSURANCE COMPANY OF CANADA (U.S.) (File No. 333-168712) under the Securities Act of 1933 and to deliver and file the same, with exhibits thereto, and other amendments in connection therewith, with the Securities and Exchange Commission, hereby ratifying and confirming all that each of said attorneys-in-fact or his or her substitute or substitutes may do or cause to be done by virtue hereof.

This power will expire no later than twelve months from date of execution.

IN WITNESS WHEREOF, I set my hand on the date shown.

/s/ Ronald H. Friesen

Ronald H. Friesen

Dated: August 3, 2013

Masters Flex II

SUN LIFE ASSURANCE COMPANY OF CANADA (U.S.)

POWER OF ATTORNEY

I, Michael K. Moran, hereby constitute and appoint Michael S. Bloom, Kenneth N. Crowley, Maura A. Murphy, and Christine McGeough, and each of them, my attorneys-in-fact, each with the power of substitution, for me in any and all capacities, to sign any Post-Effective Amendments to the Registration Statement of SUN LIFE ASSURANCE COMPANY OF CANADA (U.S.) (File No. 333-168712) under the Securities Act of 1933 and to deliver and file the same, with exhibits thereto, and other amendments in connection therewith, with the Securities and Exchange Commission, hereby ratifying and confirming all that each of said attorneys-in-fact or his or her substitute or substitutes may do or cause to be done by virtue hereof.

This power will expire no later than twelve months from date of execution.

IN WITNESS WHEREOF, I set my hand on the date shown.

/s/ Michael K. Moran

Michael K. Moran

Dated: August 3, 2013

Masters Flex II

SUN LIFE ASSURANCE COMPANY OF CANADA (U.S.)

POWER OF ATTORNEY

I, James D. Purvis, hereby constitute and appoint Michael S. Bloom, Kenneth N. Crowley, Maura A. Murphy, and Christine McGeough, and each of them, my attorneys-in-fact, each with the power of substitution, for me in any and all capacities, to sign any Post-Effective Amendments to the Registration Statement of SUN LIFE ASSURANCE COMPANY OF CANADA (U.S.) (File No. 333-168712) under the Securities Act of 1933 and to deliver and file the same, with exhibits thereto, and other amendments in connection therewith, with the Securities and Exchange Commission, hereby ratifying and confirming all that each of said attorneys-in-fact or his or her substitute or substitutes may do or cause to be done by virtue hereof.

This power will expire no later than twelve months from date of execution.

IN WITNESS WHEREOF, I set my hand on the date shown.

/s/ James D. Purvis

James D. Purvis

Dated: August 3, 2013

Masters Flex II

SUN LIFE ASSURANCE COMPANY OF CANADA (U.S.)

POWER OF ATTORNEY

I, Frank K. Neill, III, hereby constitute and appoint Michael S. Bloom, Kenneth N. Crowley, Maura A. Murphy, and Christine McGeough, and each of them, my attorneys-in-fact, each with the power of substitution, for me in any and all capacities, to sign any Post-Effective Amendments to the Registration Statement of SUN LIFE ASSURANCE COMPANY OF CANADA (U.S.) (File No. 333-168712) under the Securities Act of 1933 and to deliver and file the same, with exhibits thereto, and other amendments in connection therewith, with the Securities and Exchange Commission, hereby ratifying and confirming all that each of said attorneys-in-fact or his or her substitute or substitutes may do or cause to be done by virtue hereof.

This power will expire no later than twelve months from date of execution.

IN WITNESS WHEREOF, I set my hand on the date shown.

/s/ Frank K. Neill, III

Frank K. Neill, III

Dated: August 3, 2013

Masters Flex II

SUN LIFE ASSURANCE COMPANY OF CANADA (U.S.)

POWER OF ATTORNEY

I, Daniel J. Towriss, hereby constitute and appoint Michael S. Bloom, Kenneth N. Crowley, Maura A. Murphy, and Christine McGeough, and each of them, my attorneys-in-fact, each with the power of substitution, for me in any and all capacities, to sign any Post-Effective Amendments to the Registration Statement of SUN LIFE ASSURANCE COMPANY OF CANADA (U.S.) (File No. 333-168712) under the Securities Act of 1933 and to deliver and file the same, with exhibits thereto, and other amendments in connection therewith, with the Securities and Exchange Commission, hereby ratifying and confirming all that each of said attorneys-in-fact or his or her substitute or substitutes may do or cause to be done by virtue hereof.

This power will expire no later than twelve months from date of execution.

IN WITNESS WHEREOF, I set my hand on the date shown.

/s/ Daniel J. Towriss

Daniel J. Towriss

Dated: August 3, 2013

Masters Flex II

SUN LIFE ASSURANCE COMPANY OF CANADA (U.S.)

POWER OF ATTORNEY

I, Michael S. Bloom, hereby constitute and appoint Kenneth N. Crowley, Maura A. Murphy, and Christine McGeough, and each of them, my attorneys-in-fact, each with the power of substitution, for me in any and all capacities, to sign any Post-Effective Amendments to the Registration Statement of SUN LIFE ASSURANCE COMPANY OF CANADA (U.S.) (File No. 333-168712) under the Securities Act of 1933 and to deliver and file the same, with exhibits thereto, and other amendments in connection therewith, with the Securities and Exchange Commission, hereby ratifying and confirming all that each of said attorneys-in-fact or his or her substitute or substitutes may do or cause to be done by virtue hereof.

This power will expire no later than twelve months from date of execution.

IN WITNESS WHEREOF, I set my hand on the date shown.

/s/ Michael S. Bloom

Michael S. Bloom

Dated: August 3, 2013

Masters Flex II