A solution nucleic acid hybridization assay for detecting a target nucleic acid that comprises first and second nucleic acid sequences comprising: (a) contacting the target nucleic acid under hybridizing conditions with a sulfonic acid polymer or a salt thereof and an excess of (i) a label extender probe comprising first and second segments, wherein the first segment is complementary to the first nucleic acid sequence of the target nucleic acid and (ii) a capture extender probe comprising first and second segments, wherein the first segment is complementary to the second nucleic acid sequence of the target nucleic acid; (b) contacting under hybridizing conditions the product of step (a) with a capture probe bound to a solid phase that is complementary to the second segment of the capture extender probe; (c) removing materials not bound to the solid phase; (d) contacting under hybridizing conditions the solid phase complex product of step (c) with a nucleic acid multimer that comprises (i) a preamplifier probe that is complementary to the second segment of the label extender probe and (ii) a multiplicity of amplifier probes; (e) removing unbound nucleic acid multimer; (f) contacting under hybridizing conditions the solid phase complex product of step (e) with a labeled oligonucleotide that is complementary to the amplifier probes of the nucleic acid multimer; (g) removing unbound labeled oligonucleotide; and (h) detecting the presence of labeled oligonucleotide in the solid phase complex product of step (g), wherein the sulfonic acid polymer or salt thereof in step (a) is of general formula or: or a salt thereof, wherein: R 1 is hydrogen or C 1-6 aliphatic; L is a covalent bond or C 1-6 alkylene; R 3 is hydrogen or C 1-6 alkyl; and n is an integer of 10 or more, wherein the sulfonic acid polymer or salt thereof has an average molecular weight of less than 10,000 Da. (a) contacting the target nucleic acid under hybridizing conditions with a sulfonic acid polymer or a salt thereof and an excess of (i) a label extender probe comprising first and second segments, wherein the first segment is complementary to the first nucleic acid sequence of the target nucleic acid and (ii) a capture extender probe comprising first and second segments, wherein the first segment is complementary to the second nucleic acid sequence of the target nucleic acid; (b) contacting under hybridizing conditions the product of step (a) with a capture probe bound to a solid phase that is complementary to the second segment of the capture extender probe; (c) removing materials not bound to the solid phase; (d) contacting under hybridizing conditions the solid phase complex product of step (c) with a nucleic acid multimer that comprises (i) a preamplifier probe that is complementary to the second segment of the label extender probe and (ii) a multiplicity of amplifier probes; (e) removing unbound nucleic acid multimer; (f) contacting under hybridizing conditions the solid phase complex product of step (e) with a labeled oligonucleotide that is complementary to the amplifier probes of the nucleic acid multimer; (g) removing unbound labeled oligonucleotide; and (h) detecting the presence of labeled oligonucleotide in the solid phase complex product of step (g), R 1 is hydrogen or C 1-6 aliphatic; L is a covalent bond or C 1-6 alkylene; R 3 is hydrogen or C 1-6 alkyl; and n is an integer of 10 or more,